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DOCUMENT RESUME
ED 070 647 SE 015. 367
TITLE Air Quality Criteria for Particulate Matter.INSTITUTION National Air Pollution control Administration (DHEW),
Washington, D.C.REPORT NO NAPCA-AP-49PUB DATE Jan 69NOTE 218p.
EDRS PRICE MF-$0.65 HC-$9.87DESCRIPTORS *Air Pollution Control; *Environmental Criteria;
Environmental Influences; *Literature Reviews;*Matter; Pollution; Quality Control; Standards
ABSTRACTTo assist states in developing air quality standards,
this book offers a review of literature related to atmosphericparticulates and the development of criteria for air quality. It notonly summarizes the current scientific knowledge of particulate airpollution, but points up the major deficiencies in that knowledge andthe need for further research. Focused upon is total particulatematter of the kind' normally measured by high--Volume and paper-tapesampling methods and by dustfall collection. Further, it considersthe effects of particulate matter conjunction with some gaseousmaterials where important synergistic effects are observed. Methodsof measuring the effects of particulate matter on meteorologicalconditions, atmospheric visibility, materials, and vegetation aredocumented, as well as the resulting economic loss. Public awarenessof air pollution and the role of particulate matter in the odorproblem are assessed. There is a chapter on the respiratory system,discussing particulate deposition therein and removal therefrom,necessary to understanding the final chapters which surveytoxicological effects of particulate'matter and the epidemiologicaldata for man and animals. A glossary of terms, lists of symbols,abbreviations, and conversion factors for various units ofmeasurement, author index* and subject index are provided. (BL)
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U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFAREPublic Health Service
Consuiner Protection and Environmental Health Service
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ERRATA FOR
AP-49.
AIR QUALITY CRITERIA FOR PARTICULATE MATTER
Page 37, Fig. 2-7: Fill in dots on right-hand curve. (to agree with key)
Page 65, col. 2, para. 2, line 3: "sol serve as . . ." should be "sols
serve as . . "I
Page 68, col. 1, line 2: ". . . Kearney,10
it" should be ". . . Kearney.10
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Page 68, col. 2, Fig. 4-2: The bottom curve in the figure (i.e., State
College, Pa.) should contain four filled-in circles; i.e., the first
circle should be filled in.
Page 69, col. 1, para. 3, line 2: H. . . where pervious metals" should be
". . . where precious metals"
Page 69, col. 2, para. 3, lines 6-7: "buildings in burning soot-producing
fuel cities.15-17,
should be "buildings in cities burning soot-producing
1S-17"fuel.
Page 69, col. 2, para. 3, 18th line: "less resistant tyes of mason-" should
be "less resistant types of mason-"
Page 69, col. 2, para. 4, line 5: "clean the smoke and" should be "clean
the soot and"
Page 72, col. 1, para. 1, line 11: "conditions; show . . ." should be
"conditions show . .
Page 73, col. 1, para. 2, lines 3-4: "are due only to differences in parti-
culate matter, since there are significant . . ." should be "are due
not only to differences in particulate matter, but also to significant . ."
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Page 89, col. 2, para. 2, line 11: "Czaja3 -6" should be "CzajaS ,8,15,16"
Page 90, col. 2, line 1: "the rate of 0.47 mg/cm2-day and then ex-" should
be "the rate of 0.47 mg/cm2-day, a relatively high rate, and then ex-"
Page 90, Fig. 6-1, line 1 of title: "Damp" should be "Dry"
Page 92, col. 2, para. 2, lines 6 and 7: "0.75 g/m2-day to 1.5 g/m2-day"
should be "750 mg/m2-day to 1500 mg/m2-day."
Page 92, col. 2, para. 3, lines 8, 10, 11, and 12: "1.5 g/m2-day . .
2/5 g/m2-day . . . 3.8 g/m2-day" should be "1500 mg/m2-day . .
2500 mg/m2-day, and 3800 mg/m2 -clay."
Page 96, ref. 6 and 22: "Allgem. Forstz" should be "Allgem. Forst Zeitschrifte."
Page 139, col. 2, line 13:' "hematite" should be hematite"
Page 162, col. 1, para. 1, line 3: "Anderson30" should be "Anderson32"
Pages 171-175, Table 11-6, 4th col. heading: "(in brackets) or dustfall
tons/mi2-mo" should be "COH (in brackets) or dustfall, tons/mi
2-mo.
Page 186, col. 2, para. 3, line. 12: "tons /m2- month)" should be "tons/mi 2-mo)"
( , Page 188, col. 2, para. 5, line 6: "C-4)" should be "C -S)."
Page 188, col. 2, para. 6, line 8: "C-3)" should be "C-5)."
Page 188, col, 2, pala. 7, line 2: ". . . particulates on a 24-hour average,"
should be ". . . particulates (6-month average)."
Page 189, col. 1, line 1: "Section C-5)" should be "Section C-2d)"
Page 189, col. 1: Add to line 8 "(British Data; see Chapter 11, Section C-3)."
Page 189, col. 1, para. 3, line 6: "C-2" should be "C-2b."r.
-Page 189, col. 1, para. 4, line 4: ". . . about 30 mg/cm2-mo,- should be
2"0,3 mg/cm -mo.'
AIR QUALITY CRITERIA
FOR
PARTICULATE MATTER
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health ServiceConsumer Protection and Environmental Health Service
National Air Pollution Control Administration
Washington, D.C.
January 1901
National Air Pollution Control Administration Publication No. AP-49
a
Preface
Air quality criteria tell us what science hasthus far been able to measure of the obviousas well as the insidious effects of air pollu-tion on man and his environment. Such cri-teria provide the most realistic basis that wepresently have for determining to what pointthe levels of pollution must be reduced if weare to protect the public health and welfare.
The criteria that we can issue at the pres-ent time do not tell us all that we would liketo know. If all of man's previous experiencein evaluating environmental hazards pro-vides us with a guide, it is likely that im-proved knowledge will show that there areidentifiable health and welfare hazards as-sociated with air pollution levels that were.previously thought to be innocuous. As ourscientific knowledge grows, air quality cri-teria will have to be reviewed and, in allprobability, revised. But the Congress hasmade it clear that we are expected, withoutdelay, to make the most effective use of theknowledge we now have.
The Air Quality Act of 1967 requires thatthe Secretary of Health, Education, and Wel-fare ". . . from time to time, but as soon aspracticable, develop and issue to the Statessuch criteria of air quality as in his judgmentmay be requisite for the protection of thepublic health and welfare. . . . Such criteriashall . . . reflect the latest scientific knowl-edge useful in indicating the kind and extentof all identifiable effects on health and wel-fare which may be expected from the pres-ence of an air pollution agent. ..."
Under the Air Quality Act, the issuance ofair quality criteria is a vital step in a pro-gram designer to assist the States in takingresponsible technological, soicial; and politi-cal action to protect the public from the ad-verse effects of air pollution.
Briefly, the Act calls for the Secretary ofHealth, Education, and Welfare to define the
broad atmospheric areas of the Nation inwhich climate, meteorology, and topography,all of which influence the capacity of air todilute and disperse pollution, are generallyhomogeneous.
Further, the Act requires the Secretary todefine those geographical regions in thecountry where air pollution is a problemwhether interstate or intrastate. These airquality control regions will 1>e designated onthe basis of meteorological, social, and po-litical factors which suggest that a group ofcommunities should be treated as a unit forsetting limitations on concentrations of at-mospheric pollutants. Concurrently, the Sec-retary is required to issue air quality criteriafor those pollutants he believes maybe harm-ful to health or welfare, and to publish re-lated information on the techniques whichcan be' employed to control the sources ofthose pollutants.
Once these steps have been taken for anyregion, and for any pollutant or combinationof pollutants, then the State or States respon-sible for the designated region are on noticeto develop ambient air quality standards ap-plicable to the region for the pollutants in-volved, and to develop plans of action forimplementing the standards.
The Department of Health, Education, andWelfare will review, evaluate and approvethese standards and plans, and once they areapproved, the States will be expected to takeaction to control pollution sources in the man-ner outlined in their plans.
At the direction of the Secretary, the Na-tional Air Pollution Control Administrationhas established appropriate programs tocarry out the several Federal responsibilitiesspecified% the legislation.
Air Quality Criteria for Particulate Mat-.ter is the culmination of intensive and dedi-cated effort on the part of many personsso
iii
ti
r.
many, in fact, that it is not practical to nameall of them.
In accordance with the Air Quality Act, aNational Air Quality Criteria Advisory Com-mittee was established, having a member-ship broadly representative of industry, uni-versities, conservation interests, and all lev-els of government. The committee, whosemembers are listed following this discussion,provided invaluable advice on policies andprocedures under which to issue criteria, andprovide major assistance in drafting thisdocument. To facilitate the committee's work,subcommittees were formed to provide inten-sive efforts relating to specific pollutantsinitially for particulate matter and for sul-fur oxides.
With the help of the Subcommittee on Par-ticulate Matter, expert consultants were re-tained to draft portions of this document,with other segments being drafted by staffmembers of the National Air Pollution Con-trol Administration. After the initial draft-ing, there followed a sequence of review andrevision by the subcommittee, and by the fullcommittee, as well as by individual review-ers especially selected for their competenceand expertise in the many fields of scienceand technology related to the problems of at-
iv
mospheric pollution by particulate matter.These efforts, without which this documentcould not have been completed successfully,are acknowledged individually on the follow-ing pages.
As also required by the Air Quality Act of1967, appropriate Federal departments andagencies, also listed on the following pages,were consulted prior to issuing this criteriadocument. A Federal consultation committee,comprising members designated by the headsof seventeen departments and agencies, re-viewed the document, and met with staff per-sonnel of the National Air Pollution ControlAdministration to discuss their comments.
This Administration is pleased to acknowl-edge the efforts of each of the persons specif-ically named, as well as the many not namedwho contributed to the publication of thisvolume. In the last analysis, however, the Na-tional Air .Pollution Control Administrationis responsible for its content.
JOHN T. MIDDLETON,
Commissioner, National Air PollutionControl Administration
NATIONAL AIR QUALITY CRITERIA ADVISORY COMMITTEE
ChairmanDR. JOHN T. MIDDLETON, Commissioner
National Air Pollution Control Administration
Dr. Herman R. Amberg.Manager, Manufacturing Services Dept.Central Research DivisionCrown Zellerbach Corp.Camas, Wash.
Dr. Nyle C. BradyDirector, Agricultural Experiment
StationCornell UniversityIthaca, N.Y.
Dr. Seymour CalvertDirector, Statewide Air Pollution
Research CenterUniversity of California, RiversideRiverside, Calif.
Dr. Adrian Ramond ChamberlainVice PresidentColorado State UniversityFort Collins, Colo.
*Dr. Raymond F. DasmannSenior EcologistConservation FoundationWashington, D.C.
Mr. James R. GarveyPresident and DirectorBituminous Coal Research, Inc.Monroeville, Pa.
Dr. David M. GatesDirectorMissouri Botanical GardensSt. Louis, Mo.
* Resigned, October 14, 1968.
Dr. Neil V. HakalaPresidentEsso Research & Engineering Co.Linden, N.J.
Dr. Ian T. HigginsProfessor, School of Public.HealthThe University of MichiganAnn Arbor, Mich.
Mr. Donald A. JensenExecutive EngineerFord Motor Co.Dearborn, Mich.
Dr. Herbert E. KlarmanProfessor of Public Health Administration
and Political EconomySchool of Hygiene and Public HealthJohns Hopkins UniversityBaltimore, Md.
Dr. Leonard T. KurlandProfessor of EpidemiologyMayo Graduate School of MedicineHead, .Medical StatisticsEpidemiology and Population Genetics
Section, Mayo ClinicRochester, Minn.
Dr. Frederick Sargent IIDean, College of Environmental
SciencesUniversity of WisconsinGreen Bay, Wis.
Mr. William J. StanleyDirector, Jhicago Department of
Air Pollution ControlChicago, Ill.
CONTRIBUTORS AND REVIEWERS
Dr. Donald F. AdamsHead, Air Pollution Research DivisionCollege of EngineeringWashington State UniversityPullman, Wash.
Dr. Mary 0. AmdurAssociate Professor of ToxicologyDepartment of PhysiologySchool of Public HealthHarvard UniversityBoston, Mass.
Dr. Rodney R. BeardExecutive Head, Department
of Preventive MedicineStanford University Medical SchoolPalo Alto,. Calif.
Dr. Francis E. BlacetEmeritus Professor of ChemistryUniversity of California at Los AngelesLos Angeles, Calif.
Dr. L. J. BrasserHead, Atmospheric Pollution DivisionResearch Institute for
Public Health EngineeringDelft, The Netherlands
Dr. Leslie A. ChambersProfessor and ChairmanDepartment of Environmental HealthSchool of Public HealthUniversity of TexasHouston, Tex.
Dr. Robert CharlsonResearch Associate Professor of
Atmospheric ChemistryDepartment of Civil EngineeringUniversity of WashingtonSeattle, Wash.
Dr. Morton CornAssociate Professor, Department of
Occupational HealthGraduate School of Public HealthUniversity of PittsburghPittsburgh, Pa.
vi
Dr. Ellis F. DarleyPlant PathologistStatewide Air Pollution Research CenterUniversity of California at RiversideRiverside, Calif.
Dr. Arthur DuBoisDepartment of PhysiologyGraduate School of MedicineUniversity of PennsylvaniaPhiladelphia, Pennsylvania
Dr. James G. EdingerProfessor of MeteorologyUniversity of CaliforniaLos Angeles, Calif.
Dr. Lars FribergChief, Department of HygieneKarolinska Institute of HygieneStockholm, Sweden
Dr. Sheldon K. FriedlanderProfessor of Chemical Engineering
and Environmental Health EngineeringCalifornia Institute of TechnologyPasadena, Calif.
Dr. John R. GoldsmithChief, Environmental Hazards
Evaluation UnitDepartment of Public HealthState of CaliforniaBerkeley, Calif.
Dr. Leonard GreenburgProfessor of Preventive and
Environmental MedicineAlbert Einstein College of MedicineNew York, N.Y.
D. Alexander GoetzSenior r3tr.rf ConsultantNational Center for Atmospheric
ResearchAltadena, Calif.
Dr. Paul GrossDirector, Research LaboratoryIndustrial Hygiene Foundation of
America, Inc.Mellon InstitutePittsburgh, Pa.
Dr. Harry HeimannResearch Associate, Department of
PhysiologySchool of Public HealthHarvard UniversityBoston, Mass.
Dr. Walter W. HollandProfessor, Department of Clinical
Epidemiology and Social MedicineSt. Thomas' Hospital Medical SchoolUniversity of LondonLondon, England
Mr. John H. JacobsPrincipal Research PhysicistBell & Howell Research Center(Chicago, Ill.)Pasadena, Calif.
Dr. P. E. JoostingMedical ServiceResearch Institute for
Public Health EngineeringDelft, The Netherlands
Mr. Elmer R. KaiserSenior Research ScientistSchool of Engineering and ScienceNew York UniversityNew York, N. Y.
Dr. Herbert LandesmanConsulting ChemistPasadena, Calif.
Dr. Phillip A. LeightonEmeritus Professor of ChemistryStanford UniversityPalo Alto, Calif.
Dr. Mark H. LepperProfessor of Preventive MedicineUniversity of Illinois College
of MedicineChicago, Ill.
Mr. Robert H. LinnellStaff Associate, Departmental Science
Development SectionNational Science FoundationWashington, D.C.
Mr. Benjamin LinskyProfessor, Department of Civil EngineeringWest Virginia UniversityMorgantown, W. Va.
Dr. James P. LodgeProgram Scientist, National Center
for Atmospheric ResearchBoulder, Colo.
Dr. Thomas C. Lloyd, Jr.Associate Professor, Department of
PhysiologySchool of MedicineCase Western Reserve UniversityCleveland, Ohio
Mr. John A. MagaExecutive OfficerAir Resourc,:s Board, State of
CaliforniaSacramento, Calif.
Dr. Roy McCauldinProfessor, Department of Environmental
EngineeringCollege of EngineeringUniversity of FloridaGainesville, Fla.
Dr. Herbert C. McKeeAssistant Director, Department of
Chemistry and Chemical EngineeringSouthwest Research InstituteHouston, Tex.
Dr. Paul E. MorrowProfessor of Radiatibii Biology and
BiophysicsSchool of Medicine and DentistryUniversity of RochesterRochester, N. Y.
Dr. Edward D. Pa lmesProfessor of Environmental MedicineInstitute of Environmental MedicineNew York University Medical CenterNew York, N. Y.
Dr. James N. Pi , Jr.Professor of ChiimmistryUniversity of California at RiversideRiverside, Calif.
Dr. Walter A. Quebedeaux, Jr.Director, Harris County Air
and Water Pollution Control DivisionHouston, Tex.
Dr. Donald D. ReidProfessor of Epidemiology and Director
of DepartmentDepartment of Medical Statistics and
EpidemiologyLondon School of Hygiene and
Tropical MedicineLondon, England
Dr. Elmer RobinsonChairman, Environmental Research
DepartmentStanford Research InstituteMenlo Park, Calif.
Dr. Stanley N. RokawChief, Pulmonary Research SectionRancho Lcs Amigos HospitalLos Angeles, Calif.
Dr. August T. RossanoProfessor, Air Resources ProgramDepartment of Civil Engineering.University of WashingtonSeattle, Wash.
Mr. Jean J. SchuenemanChief, Division of Air Quality ControlMaryland State Department of HealthBaltimore, Md.
Dr. Wayne T. Sproul'Consultant in PhysicsPasadena, Calif.
Dr. Gordon H. StromDepartment of Aeronautical
EngineeringCollege of EngineeringNew York UniversityNew York, N. Y.
Dr. 0. Clifton TaylorAssociate DirectorStatewide Air Pollution Research CenterUniversity of California at RiversideRiverside, Calif.
viii
Dr. Moyer D. ThomasEditor. Inter-Society Committee Manual of
Methods for Ambient Air Sampling andAnalysis
Riverside, Calif.
Dr. Amos TurkProfessor, Chemistry DepartmentThe City College of the City University
of New YorkNew York, N. Y.
Mr. Hans K. UrySpecial ConsultantEnvironmental Hazards Evaluation UnitCalifornia State Department of Public HealthBerkeley, Calif.
Mr. Ralph C. WandsDirector, Advisory Center on ToxicologyNational Research CouncilWashington, D.C.
Richard P. WayneOxford UniversityLondon, EnglandVisiting Professor in PhotochemistryUniversity of California at Riverside'Riverside, Calif.
Dr. Phillip W. WestProfessor of ChemistryCollege of Chemistry and PhysicsLouisiana State UniversityBaton Rouge, La.
Dr. Warren Winkelstein, Jr.Professor and Head, Division of
EpidemiologySchool of Public HealthUniversity of CaliforniaBerkeley, Calif.
Dr. Harold WolozinProfessor and ChairmanEconomics DepartmentUniversity of MassachusettsBoston, Mass.
Mr. John E. YocomSenior Research EngineerTravelers Research Center, Inc.Hartford, Conn.
FEDERAL AGENCY LIAISON REPRESENTATIVES
Department of AgricultureKenneth E. GrantAssociate AdministratorSoil Conservation Service
Department of CommercePaul T. O'DayStaff Assistant to the Secretary
Department of DefenseColonel Alvin F. Meyer, Jr.ChairmanEnvironmental Pollution Control Committee
Department of Housing and UrbanDevelopment
Charles M. HaarAssistant Secretary for Metropolitan
Development
Department of the InteriorHarry PerryMineral Resources Research Advisor
Department of JusticeWalter Kiechel, Jr.Assistant ChiefGeneral Litigation SectionLand and Natural Resources Division
Department of LaborDr. Leonard R. LinsenmayerDeputy DirectorBureau of Labor Standards
Department of TransportationWilliam H. CloseAssistant Director for Environmental
ResearchOffice of Noise Abatement
Department of the TreasuryGerard M. BrannonDirectorOffice of Tax Antslysis
Federal Power CommissionF. Stewart BrownChiefBureau of Power
General Services AdministrationThomas E. CrockerDirectorRepair and Improvement DivisionPublic Buildings Service
National Aeronautics and SpaceAdministration
Major General R. H. Curtin, USAF (Ret.)Director of Facilities
NationcZ Science FoundationDr. Eugene W. Bier lyProgram Director for MeteorologyDivision of Environmental Sciences
Post Office DepartmentLouis B. FeldmanChiefTransportation Equipment BranchBureau of Research and Engineering
Tennessee Valley AuthorityDr. F. E. GartrellAssistant Director of Health
Atomic Energy CommissionDr. Martin B. BilesDirectorDivision of Operational Safety
Veterans AdministrationGerald M. HollanderDirector of Architecture and EngineeringOffice of Construction
AIR QUALITY CRITERIA FORPARTICULATE MATTER
TABLE OF CONTENTSChapter Page
Preface iii
Introduction xiii
1 Atmospheric Particles: Definitions, Physical Properties, SourcesConcentrations 1
2 Effects of Atmospheric Particulate Matter on Solar Radiation andand Climate Near the Ground 33
3 Effects of Atmospheric Particulate Matter on Visibility 47
4 Effects of Atmospheric Particulate Matter on Materials 63
5 Economic Effects of Atmospheric Particulate Matter 77
6 Effects of Atmospheric Particulate Matter on Vegetation 87
7 Social Awareness of Particulate Pollution 97
8 Odors Associated with Atmospheric Particulate Matter 103
9 The Respiratory System: Deposition, Retention, and Clearance ofParticulate Matter 109
10 Toxicological Studies of Atmospheric Particulate Matter 127
11 Epidemiological Appraisal of Atmospheric Particulate Matter 145
12 Summary and Conclusions 179
Appendices
ASymbols 192
BAbbreviations 193
CConversion Factors 194
DGlossary 195
Author Index 204
Subject Index 208
Acknowledgements 211
xi
INTRODUCTION
Pursuant to authority delegated to theCommissioner of the National Air PollutionControl Administration, Air Quality Criteriafor Particulate Matter is issued in accord-ance with Section 107b1 of the Clean Air Act(42 U.S.C. 1857c-2b1).
Air quality criteria are an expression ofthe scientific knowledge of the relationshipbetween various concentrations of pollutantsin the air and their adverse effects on manand his environment. They are issued to as-sist the States in developing air qualitystandards. Air quality criteria are descrip-tive; that is, they describe the effects th.lthave been observed to occur when the am-bient air level of a poliutant has reached orexceeded specific figures for a specific timeperiod. In developing criteria, many factorshave to be considered. The chemical andphysical characteristics of the pollutants andthe techniques available for measuring thesecharacteristics must be considered, alongwith exposure time, relative humidity, andother conditions of the environment. The cri-teria must consider the contribution of allsuch variables to the effects of air pollutionon human health, agriculture, materials, vis-ibility, and climate. Further, the individualcharacteristics of the receptor must be takeninto account. Table A, which appears at theend of this introduction, is a listing of themajor factors that need to be considered indeveloping criteria.'
Air quality standards are prescriptive.They prescribe pollutant exposures which apolitical jurisdiction determines should notbe exceeded in a specified geographic area,
Calvert, S. Statement for air quality criteriahearings held by the Subcommittee on Air and WaterPollution of the U.S. Senate Committee on PublicWorks. July 30, 1968.
and are used as one of several factors in de-signing legally enforceable pollutant emissionstandards.
The particulate matter commonly founddispersed in the atmosphere is composed ofa large variety of substances. Some oftheseflourides, beryllium, lead, and asbes-tos, for exampleare known to be directlyoxic, although not necessarily at levels rou-tinely found in the atmosphere today. Theremay very well be others whose toxic effectshave not yet been recognized. To evaluatefully the effects on health and welfare of thepresence of each of these substances in theair requires that they be given individual at-tention, attention as classes of similar sub-stances, or that they be considered in con-junction with other substances where syner-gistic effects may occur. Such evaluationswill be made at a later time in separate docu-ments.
This document focuses on total particulatematter of the kind normally measured byhigh-volume sampling methods, by paper-tape sampling methods, and by dustfall col-lection. Further, this document considers theeffects of particulate matter in conjunctionwith some gaseous materials, such as sulfurdioxide, where important synergistic effectsare observed. (Atmospheric sulfur oxidesare treated in detail in a companion criteriadocument: Air Quality Criteria for SulfurOxides.) No attempt is made in this docu-ment to set up dose-response relationshipsfor specific particulate pollutants. Also, thelarge and diverse contributions of agricul-tural and forest management operations toair pollution, such as insecticide spraying andslash burning, and the ingestion hazard toanimals and man of toxic particulate matterdeposited on plant materials, are treated onlyfor a few selected examples; details are be-
12 i:1
yond the scope of this document.Methods of measuring the effects of partic-
ulate matter on meteorological conditions? at-_mospheric visibility, and materials aritilocu-mented, as well as is the resulting economicloss. The effects of particulate matter arefurther considered as they relate to vegeta-tion damage. :Public awareness of air pollu-tion and the role of particulate matter in theodor problem are assessed. There is, a chap-ter on the respiratory system,'late deposition therein and removal there-from, necessary to understanding of the finalchapters which survey toxicological effectsof particulate matter and the epidemiologicaldata for man and animals.
In general, the terminology employed fol-lows usage recommended in the publicationsstyle guiie of the American Chemical So-ciety. A glossary of terms, listsof symbols andabbreviations, list-Of -conversion factors forvarious units of measurement, author index,and subject index are provided. .
The literature has been generally reviewedon a worldwide basis through March 1968.The results and conclusions of foreign in-vestigations are evaluated for their possibleapplication to the air pollution problem inthe United States. This document is not in-tended as a complete, detailed literature re-view, and it does not cite every publishedarticle related to atmospheric particulates.However, the literature has been reviewedthoroughly for information related to thedevelopment of criteria, and the documentnot only summarizes the current scientificknowledge of particulate air pollution, butpoints up the major deficiencies in thatknowledge and the need for furt er research.
Technological and economic aspects of airpollution control are considered in compan-ion volumes to criteria documents. The bestmethods available for controlling the sourcesof particulate air pollution, as well as thecosts of applying these methods, are de-scribed in: Control Techniques for Particu-late Air Pollutants.
xiv13
Table A.FACTORS TO BE CONSIDERED INDEVELOPING AIR QUALITY CRITERIA
Properties of Pollution:ConcentrationChemical compositionMineralogical structureAdsorbed gasesCoexisting pollutantsPhysical state of pollutant
SolidLiquidGaseous
Rate of transfer to receptor domainMeasurement Methods:
Hi-Vol samplerSpot-tape samplerDuet fall bucket (rate of deposition)Condensation nuclei counterImpinger (liquid filled)Cascade impactorElectrostatic precipitatorLight scattering meterChemical analysisGas analysis (non-adsorbing)Adsorbed gas analysisLight scattering or attenuation
(Ringleman or visibility observation)Colored suspensionNucleation of precipitationStabilization of fogOdorTaste
Exposure Parameters:DurationConcomitant conditions, such as
TemperaturePressureHumidity
Characteristics of Receptor:Physical characteristics'Individual susceptibilityState of healthRate and site of transfer to receptor
Responses:Effects on health (diagnosable effects, latent
effects, and effects predisposing the organismto disease) :
Human healthAnimal healthPlant. health
Effects on human comfortSoilingOther objectionable surface depositionCorrosion of materialsDeterioration of materialsEffects on atmospheric propertiesEffects on radiation and temperature
Chapter 1
ATMOSPHERIC PARTICLES: DEFINITIONS, PHYSICALPROPERTIES, SOURCES, AND CONCENTRATIONS
14
Lr
Table of ContentsPage
A. INTRODUCTION 5B. PROPERTIES OF ATMOSPHERIC PARTICULATE MATTER 8
1. Surface Properties 82. Motion 93. Optical Properties 9
C. CHEMICAL REACTIONS OF ATMOSPHERIC PARTICULATEMATTER 10
D. SOURCES OF ATMOSPHERIC PARTICULATE MATTER 10E. ATMOSPHERIC PARTICULATE MATTER IN URBAN AREAS 11
1. Suspended Particulate Matter 112. Dustfall 16
F. SAMPLING AND ANALYSIS OF ATMOSPHERICPARTICULATE MATT ER 171. Particles Larger than 10p 172. Particles 0.1p to 10p 19
a. Tape Samplers for Suspended Particulate Matter 20b. High-Volume Samplers for Suspended Particulate Matter 22
3. Particles Smaller than 0.4 23G. SIZE, CHEMICAL COMPOSITION, AND SOURCE STRENGTHS
OF 'PARTICULATE MATTER FROM SELECTED EMISSIONSOURCES 231. Open Hearth Furnaces 23
a. Chemical Composition 23b. Particle Size 23
2. Incineration 24a. Chemical Composition 24b. Particle Size 25
3. Sulfuric Acid Manufacture: Chamber Process 25a. Chemical Composition 25b. Particle Size 25
4. Sulfuric Acid Manufacture: Contact Process 25a. Chemical Composition 25b. Particle Size
_4-- 255. Cement Plants 25
a. Chemical Composition 25b. Particle Size 26
6. Motor Vehicles 26a. Chemical Composition 26b. Particle Size 26
7. Fuel Oil Combustion 26a. Chemical Composition 26b. Particle Size 27
8. Combustion of Coal 27a. Chemical Composition 27b. Particle Size 27
2 1
Page
H. SUMMARY 27
I. REFERENCES 29
List of FiguresFigure1-1 Sizes of Atmospheric Particulate Matter 6
1-2 Setting Velocities in Still Air at 0°C and 760 mm Pressure for Par-ticles Having a Density of 1 g/cm3 as a Function of Particle Diameter 7
1-3 Log-Normal Distribution of Particles Showing Various Average 7
Diameters1-4 Particle Size Distribution of Figure 1-3, Plotted Logarithmically 7
1-5 Cumulative Logprobability Curire for the Distribution ofFigure 1-4. 8
1-6 Horizontal Elutriator Cut -off Characteristics 17
1-7 Dustfall Data for Six Cities 18
List of TablesTable
1-1 Emission Inventory of Particulate Material, Tons Per Year 12
1-2 Suspended Particle Concentrations (Geometric Mean of CenterCity Station) in Urban Areas, 1961 to 1965 13
1-3 Distribution of Selected Cities by Population Class and ParticleConcentration, 1957 to 11967 15
1-4 Distribution of Selected Nonurban Monitoring Sites by Categoryof Urban Proximity, 1957 to 1967 15
1-5 Arithmetic Mean and Maximum Urban Particulate Concentrationsin the United States, Biweekly Samplings, 1960 to 1965 16
1-6 Emission Factors for Selected Categories of Uncontrolled Sourcesof Particulates 24
1681+
Chapter 1
ATMOSPHERIC PARTICLES: DEFINITIONS, PHYSICAL PROPERTIES,SOURCES, AND CONCENTRATIONS
A. INTRODUCTION
Atmospheric particles are chemically amost diverse class of substances; they do,however, have a number of physical proper-ties in common, and for this reason are gen-erally classed in a single category, sometimesreferred to as aerosols.
Some workers restrict concept of par-ticulate matter to the solid phase; this dis-tinction is, however, difficult to make in prac-tice and is probably not proper. Others referto airborne particles as nuclei because oftheir role in the nucleation of condensation,especially of liquid or solid water. In thisdocument, the term "particle" is used to meanany dispersed matter, solid or liquid in whichthe individual aggregates are larger thansingle small molecules (about 0.0002p1 in di-ameter), but smaller than about 5001L. [Onemicron (p.) is one-thousandth of a millimeteror one-millionth of a meter.] Particles in thissize range have a life-time in the suspendedstate varying from a few seconds to severalmonths.
Many disciplines are involved in the studyof particles, and each appears to have devisedits own system of nomenclature to differenti-ate classes of particles with respect to size,physical state, origin, etc. Periodic, but rath-er unsuccessful attempts have been made toresolve the confusion.1 The present documentwill discuss the several classes of particles byspecifying the size or size interval in microns(p) and, where appropriate, the physicalstate. Figure 1-1 provides a graphic schemefor relating meteorologic nomenclature foraerosols to the particle sizes. Nonsphericalparticles may be idealized as spheres whichwould have the same settling rate, but evenso, size designations have frequently been
ambiguous. For example, "size" has beentaken to mean both diameter and radius.Again some workers interpret size to meanthe physical or geometrical size, while othersmean some equivalent size based, for ex-ample, on optical laws relating the size ofaerosol particles to the measured scatteringof a light beam. In this document, "size" ordi-narily refers to particle diameter or Stokes'diameter as defined below.
Particles larger than about a micron in di-ameter settle in still air at velocities approxi-mated by Stokes' Law:
gd2 (plp2)
where18 n
v is velocity in cm/sec (settling:velocity or terminal velocity),
g is the acceleration of gravity incm /sect,is particle diameter in cm,and are the densities of theparticle and of air respectivelyin g/cm2, and
n is viscosity of air in poise.The expression is precisely true only forspheres. An upper limit to its applicability isset by the fact that, when a certain settlingvelocity is reached, the particle generates asignificant "wake". A lower limit is reachedwhen the particles become small enough,around 1p, that air resistance is no longercontinuous but is rather the result of individ-ual collisions with air molecules. Under theseconditions the particles "slip" between mole-cOes and the Stokes' equation underesti-mates their falling velocity. Correction fac-tors exist to allow for this behavior, but thyneed not be given here for the qualitative dis-cussion which follows. The approximate set-
dP1
1'7(I5
K.
k
NOMENCLATURE AitkenParticles
LargePanicles
GiantPa ticles
i
iiw 0a 11-z I-< Zx ,xtut'i 0°CO a.
2
ATOMS,MOLECULES(Not Particles)
.
AIRELECTRICITY
.
Small
Ions
Larpslons
ATMOSPHERICOPTICS Particles
CLOUDPHYSICS
ActiveCondensation
Nuclei
AIRCHEMISTRY
Main Aerosolminas*
-
ROUTINE AIRPOLLUTION
,
SuspendedParticulate Metter
>MEASUREMENTS
Dunhill
10-4 10.3 10.2
DIAMETER,,LL
FIGURE 1-1. Sizes of Atmospheric Particulate Matter' (The figure shows the ranges of particle size (diam-eter) of various types of particulate matter which are found in the earth's atmosphere.)
10 "1 100 101 102
tling velocities in still air at 0°C and 760 mmpressure for particles having a density of 1g /cm' are:
0.14t, 8 x 10-5 cm/sec; 1p, 4 X 10-3 cm/sec;10p, 0.3 cm/sec; 100p., 25 cm/sec; and1,000p, 390 cm/sec. (See Figure 1-2.)
In the case of a nonspherical particle, sub-stitution of v, g, pi, p2, and a in equation(1-1), Stokes Law, leads to a fictitous diam-eter, d, which is known as the Stokes or aer-G-IyAamic diameter. Unless otherwise stated,the word "diameter," as applied to particlessuspended in air or gas, ordinarily meansStokes diameter.
If the density, p, of the particles is notknown, it may arbitrarily be assigned a valueof 1 g/c 3 ; in this case d is no longer the"Stokes diameter" but rather the "reducedsedimentation diameter"that is, the diam-eter of a spherical particle of unit) densityhaving the same terminal fall velocity-4h stillair as the particles in question.
The geometrical diameter of a particle willbe smaller than the reduced sedimentation di-ameter if the particle has a density greatier
6 18-
than 1. A few quantitative examples can begiven:' a 1p sphere of lead with a density ofapproximately 11 has a reduced sedimenta-tion diameter of 3.4p; a bubble of air in waterwith an outer diameter of 1p and a waterfilm thickness of 0.1, and consequentlya den-sity of approximately 0.5 g/cm3has a reducedsedimentation diameter of 0.7p- Nonsphericalparticles can also be assigned a "diameter"based on their settling rate. A rectangularplate of density 1 g /cm', and dtmenzions 5 x5x 0.5p., has a reduced sedimentation diam-eter near 2p.
Some of the smallest particles may be nomore than statistical aggregations of gasmolecules which act as a particle at one in-stant and cease to exist at the next. Solidparticles and liquid droplets may be formedin the atmosphere by condensation of a va-por. So:id particles produced by abrasion orgrinding are not sphercial and are calleddust.
This discussion of size classes must notobscure the fact that there is a continuousspectrum of sizes among the particles in the
O
103
102
10 1
100cc
a.LL0
104
UO
10-2i5
3
104
1
10-5104
0.8
0.7
0.6
100 101 102 103 104DIAMETER OF PARTICLE, MICRONS
FIGURE 1-2. Settling Velocities in Still Air at 0° Cand 760 mm Pressure for Particles Having a Den-sity of 1g /cm' as a Function of Particle Diameter.(This graph shows that, for spherical particles ofunit density suspended in air near sea level, Stokeslaw applies over a considerable range of particlesizes, where the line is straight, but that correctionis required at The extremes where the line beginsto curve.)
1
atmosphere acid.ecorresponding continuousgradatior-efS1 their size-dependent propei-ties. The distribution of particle sizes usuallyencountered approximates closely a log-nor-mal distribution. In this distribejon, thefamiliar symmetrical bell-shaped probabili-ty curve appears for a frequency graph plorted against the logarithm of the particle size.In this graph, the ordinate is the number ofparticles per unit log (particle size) interval.Figures 14 and 1-4 show the direct andlogarithmic frequency distribution curves forfor the log-normal distribution. In practice, acumulative distribution is plotted on specialgraph paper with log-probability scales so
0.
0.1
0
COUNT MODE (0.61911)
COUNT MEDIAN MOMARBITRARILY SET ATONE
COUNT MEAN (1.27211)
DIAMETER OF AVERAGEMASS (2.056p)
AREA MEDIAN (2.61411)
AREA MEAN (3.324p)
MASS MEDIAN (4.2261)
MASS MEAN(5.37411)
2 3 4 5
PARTICLE DIAMETER, ti
FIGURE 1-3. Log-normal Distribution of Particlesshowing Various Average Diameters.' (The graphis drawn from probability theory, assuming a countmedian diameter of lib and shows the numericalvalues relative to that diameter of several otherweighted average diameters discussed in the text.)
z.0.
Na
<cc
a.
0z0.2
Ccc 0.1u.
100 101PARTICLE SIZE,I1
102
nouns 1-4. Particle Size Distribution of Figure 1-3,Plotted Logarithmically. (If the particle size distri-bution is log-normal, the graph is symmetricalwhen plotted logarithmically. The figure should becontrasted with Figure 1-3.)
7
'4
that a straight line is obtained if the distribu-tion is truly log normal; the best line is fittedeither by eye or mathematically. Such a plotis shown in Figure 1-5, and the experimentalpoints give an idea of the extent to which thesize distribution of a typical industrial dustapproximates to log-normal.
A distribution curve based on an exactmathematical function can be specified interms of two parameters. In the case of thelog-normal distribution, two frequently useddefining parameters are (1) the most proba-ble size, which in this distribution is identicalwith the geometric mean, M,, and (2) thegeometric standard deviation, ag. It can beshown that the 50 percent point of the cumu-lative graph (Figure 1-5) corresponds to
0.1 1 5 10 50
CUMULATIVE, %
FIGURE 1-5. Cumulative Log-probability Curve forthe Distribution of Figure 1-4. (In a cumulativeplot, the experimental points fall on a straight linewhen the size distribution is log-normal. The 50%point corresponds to the geometric mean, M,(about 111, in this case) and the ratio of the 84.1%point to this (about 22/11 or 2, in this case) isthe geometric standard deviation, a,. In practice,the experimental points usually lie near a straightline, as shown.)
Ms, while the ratio of the 84.1 percent pointto the 50 percent point is fry
Several averages of particle size may beemployed and these may be based on aver-ages of numbers, areas, masses, etc. Some ofthe most important averages are indicated inFigure 1-3, and the numerical values cal-culated for the distribution are given relativeto a count (number) median diameter of 11,.4The terms used are self-descriptive; half of
8
the quantity (e.g., mass) lies on either side ofa median diameter, while a mean value refersto the diameter of particles possessing a spe-cific weighted average of a quantity. A moreextensive mathematical treatment of thesequantities is given in books by Cad le 5 and byDrinker and Hatch.6
B. PROPERTIES OF ATMOSPHERICPARTICULATE MATTER
Since particulate matter may consist ofsuch a wide variety of substances, .a discus-sion of chemical properties of the class can-not be specific. Some selected chemical prop-erties of important individual species will bediscussed later in connection with analyticalmethods. Biological properties are most con-veniently grouped in terms of the effectsproduced.
Many physical properties are equally di-verse. Diamond particles are harder thangypsum particles of the same size, whilehardness in this sense has no meaning forliquids. Shapes are just as varied, althoughthere is a general tendency towards sphericalshape with decreasing size as surface energy(which is a minimum for spheres) predomi-nates over crystal energy. Only three generalclasses of physical properties can reasonablybe said to apply to all particulate matter.These properties all involve the interfacebetween the particle and its1 surroundings,and they are (1) surface properties, (2) mo-tions, and (3) optical properties. A discu'.-sion of the properties of aerosols has beengiven by Corn,2 and it should be used to ex-tend the remarks offered below.
1. Surface PropertiesSurface properties include sorption, nu-
cleation, adhesion, etc. Sorptive behavior canbest be understood by considering the impactof individual molecules on the particle sur-face. If this impact is perfectly elastic andrebound is truly instantaneous, nothing hap-pens. If, however, rebound is delayed or thevelocity of rebound is smaller than that ofimpact, then there will be a local accumula-tion of the gas on or near the particle surface.If the delay is great, a substantial fraction ofthe surface may be covereda phenomenonknown as adsorption. If the delay is caused
fi
specifically by a chemical interaction betweenthe surface and the gas, the process is knownas chemisorption. Absorption refers to thesituation in which the gas is dissovled intothe particle.
A vapor (i.e., a gas below its critical tem-perature), present in amounts comparable toits equilibrium vapor pressure, may lead toa deepened sorbed layer, which then takes onthe character of a layer of true liquid or solid.If the vapor is supersaturated, a droplet orcrystal may grow by further condensation onthe sorbed layer. The net result is nucleation,a phenomenon which deserves more consid-eration. A pure vapor, free of particles, mustbe highly supersaturated before a condensedphase will form from it, because an energybarrier separates the molecular from the par-ticulate state.
Two like molecules of gas will not general-ly stick together, and an aggregate of threemolecules is still less likely to retain its iden-tity for any length of time. A wall aggregateof molecules is therefore unstable. On theother hand, if a particle is split in two, energyis required to create the new surfaces, sincethe combined surface area of the two frag-ments is greater than that of the originalparticle (surface energy increases with a de-crease in size). At some point, these twotrends of decreasing stability meet at a maxi-mum which corresponds to a certain particlesize. If a molecular aggregate can reach thissize, then the addition of a single moleculeputs it over the energy barrier and it will be-come more stable by collecting still more mol-ecules. Conversely, the loss of a single mole-cule from a nucleus 0 critical size can de-stroy its stability with the probable resultthat it will return to the molecular or gaseousstate.
The important point is that the criticalparticle generally contains some tens of mole-cules which must all come together at once.Unless the vapor concentration is high, thisis an improbable event; for some substances,homogeneous nucleation may even requiresupersaturations of many hundredfold. }low:,ever, a complete sorbed layer on a particlesurface behaves like a drop of the same diam-eter as the particle, and the energy barrier toproducing a droplet is avoided. Since parti-
des are always present in the atmosphere,nucleation on them is of widespread occur-rence.
The last of the surface properties of conse-quence is adhesion. All available evidencesuggests that solid particles with diametersless than lft (and liquid particles regardlessof size) always adhere when they collidewith each other or with a larger surface.Other factors being equal, reentrainment orrebound becomes increasingly probable withincreasing particle size. Alternatively, theadhesive property can be considered in termsof the surface energy of small particles orin terms of the more complex shear forcesacting to dislodge the larger particles.
2. Motion
The second major class of properties com-mon to all particles, regardless of composi-tion, is their mode of motion. Particles withsizes less than 0.1tt undergo large random(Brownian) motions caused by collision withindividual molecules. Particles larger thanltt have significant settling velocities, andtheir motions can vary significantly from themotion of the air in vich they are borne.For particles between 0.1/4 and ltt, settlingvelocities in still air, though finite, are smallcompared with air motions. Despite fairlyhigh concentratiors, coagulation is some-what slower as compared with particlessmaller than 0.1p because of decreasedBrownian motion. Nevertheless, the oper-ation of this mechanism, together with theprocesses which generate larger particles andwhich remove particles from the air, causesthe whole population of particulate matter inthe air to tend towards a constant size dis-tribution.
Although actual settling times in the "at-mosphere tend to differ from those computedfrom Stokes Law, because turbulence tendsto offset gravitational fall, the particleslarger than kt or 10tt are removed to a largeextent by gravity and other inertial proc-esses.
3. Optical Properties
The final class of physical properties tobe discussed is that of the behavior of par-ticles towards light. This behavior is clearly
21 9
of importance in effects on visibility, and itis through their optical effects that particlesare usually perceived in the atmosphere.Once again, particles in the size range 0.1pto 1L exhibit properties showing a transitionbetween two extreme cases.
Particles below 0.1p are sufficiently smallcompared to the wavelength of light to obeyapproximately the same laws of light scatter-ing as molecules do. This so-called Rayleighscattering varies as the sixth power of theparticle diameter and is fairly inconsequen-tial in its effects on visibility. On the otherhand, particles very much larger than 1pare so much larger than the wavelength ofvisible light that they obey the same lawsas macroscopic objects, intercepting or scat-tering light roughly in proportion to theircross-sectional area. Particles in the inter-mediate size range obey complex scatteringlaws set forth by Mie; r these laws are be-yond the scope of the present discussion. Be-cause the particle dimensions are of the sameorder of magnitude as the wavelength of visi-ble radiation, interference phenomena playa complicating role, and a given scatteringbehavior may correspond to several particlesizes. Unfortunately, this is precisely thesize range which is most effective is lightscattering and thus most needful of study.A more complete discussion of optical effectsis given in Chapter 3.
C. CHEMICAL REACTIONS OFATMOSPHERIC PARTICULATE
MATTER
In view of the diverse chemical composi-tions of particles, it is not possible to makegeneral statements about the chemical reac-tions of particulate atmospheric pollutants,and the following discussion refers to somespecific reaction systems that have beenstudied. Both particle-gas and particle-par-ticle reactions can occur, but the latter classhas been studied to an even lesser extentthan the former. Such particle-particle re-actions shout,d certainly occur in the sizerange below 0.1,L where collision betweenparticles is frequent, 'but, in particles largeenough to be readily studied, collisions arerelatively infrequent in the atmosphere be-cause of low concentrations. Samples of par-
10
tides collected on filters may, however, reactand subsequent analysis can be very mislead-ing if this fact is not taken into account.
One of the particle-gas systems, the reac-tion between sulfuric acid mist and ammoniagas, was investigated by Robbins and Cadle.8At high humidities the reaction rate was lim-ited by diffusion of ammonia to the mistdroplets. At low humidities the dropletswere viscous enough to result in diffusion ofthe reaction product away from the surfaceof the drops being the rate-determining step.This work shows the effect of accumulationof reaction products, and attempts to explainthe role of humidity in a gas-particle reac-tion.
Goetz and Pueschel reported a studywhich fully reveals the complexity of evena simplified model of the photochemical airpollution found in Los Angeles. The oneclear relationship is that the amount of re-action product deposited on nuclei suppliedfrom the gas phase is proportional to thesurface area of the nuclei. The humidity ef-fect is complex and depends upon theamounts and the order bt.asidition of theother substances present. The obvious re-actants (olefins, nitrogen dioxide, and sul-fur dioxide) differ in action as well. Amountsof sulfur dioxide of the order of 2 ppmdepress aerosol formation, while largeramounts (15-16 ppm) increase it. Nitrogendioxide is more effective if mixed with nucleibefore mixing with the olefin.
Interactions between sulfur dioxide andmetal oxide aerosols have recently been stud-ied by Smith et al." at ambient conditions oftemperature and humidity. In measurementsthat included an adsorption isotherm for sul-fur dioxide on dispersed particles, preferen-tial chemisorption on iron oxide and alumi-num oxide aerosols was observed at lowsulfur dioxide concentrations (up to 2 ppm)followed by multilayered physical adsorptionat higher concentrations.
D. SOURCES OF ATMOSPHERIC r. .4PARTICULATE MATTER
In a broad sense, particles in the abno,q-phere are produced by two mechanisms:those in the size range below 1ig arise prin-cipally by condensation, while larger par-
1
tides result from comminution, althoughthere is considerable overlap. For example,Preining et al." showed the presence ofmany particles smaller than 1p in the sprayfrom a nebulizer, while the formation of verysmall drops during the rupture of bubbleshas been demonstrated." Dry grinding proc-esses are rarely efficient in producing par-ticle sizes below a few microns because ofthe rapid increase in energy necessary toproduce the additional surface.
Combustion is complex in that it may pro-duce four distinct types of particles. Thesemay arise in the following ways:
1. The heat may vaporize material whichsubsequently condenses to yield parti-cles in the size range between 0.1p and1p,
2. the energy available produces particlesof very small size (below 0.1p) ; theseparticles may be of short life as a resultof their being unstable molec-ular clusters,
3. mechanical processes may reduce eitherfuel or ash to particle sizes larger than1p and may entrain it,
4. if the fuel is itself an aerosol duringcombustion, a very fine ash may escapedirectly, and
5. partial combustion of fossil fuels mayresult in soot formation.
Particles larger than 10p frequently re-sult from mechanical processes such as winderosion, grinding, spraying, etc., althoughraindrops, snowflakes, hailstones, or sleetare obviously not produced in this way.
The sources of dust are usually apparent.For example, a dustfall sample nearly alwayscontains particles of local soil. Another largefraction will be materials dropped on theground and pulverized by vehicles, pedestri-ans or wind action. Although actual sootflocs are increasingly absent as better homeheating is used, there may be partially burnttrash from inefficient incinerators. Finally,the process dust characteristic of local in-dustry will be present. In urban locationsparticles between 1p. and 10µ generally re-flect industrial and combustion processeswith some local soil also present. In mari-time locations, the bulk of the airborne sea
salt will be found in particles of this size.The finer process dusts (ash, etc.) also fallinto this category. In short, atmosphericparticles in the 1-p to 10-p range tend to havea composition characteristic of local sourcesand soil.
As mentioned before, it is difficult to formsmall particles by size reduction. The classof particles between 0.1p and 1p comparedwith the larger particles therefore tends tocontain increasing amounts of condensationproducts. Products of combustion begin topredominate together with photochemicalaerosols. Particles below 0.1p have not beencharaderized chemically but the increaseover the natural level, characteristic of cities,seems to be entirely the result of combustion.
Table 111 shows typical particulate emis-sion source data. Section G-1 gives sometypical analytical data on particulate matterby industry source.
E. ATMOSPHERIC PARTICULATEMITER IN URBAN AREAS
. 1. Suspended Particulate Matter
The fraction of aerosol mass in the par-ticles below 0.1p is small and concentrationsare normally reported in number per unitvolume. Even the cleanest air rarely containsfewer than some hundreds of particles percubic centimeter, and the particle count invery polluted urban air " may reach 103/cma.
The bulk of current data on suspendedparticles generally does not discriminate onthe basis of size. Most data come from theNational Air Surveillance Network (former-ly the National Air Sampling Network.l 13Blifford 20 has applied factorial analysis tothese data to show relationships among in-dividual pollutant species. Average sus-pended particle mass concentrations rangefrom about -10 pg/m3 in remote nonurbanareas to about 60 pg/m3 in near urban loca-tions. In urban areas, averages range from60 pg/m3 to 220 pg/m3, depending on the sizeof the city and its industrial activity. Inheavily polluted areas, values of up to 2000items have been recorded.
Table 1-2 lists the average suspended par-ticle concentrations for a number of stand-ard metropolitan statistical areas through-
. silo,.11
Table 1-1.-EMISSION INVENTORY OF PARTICULATE MATERIAL, TONS PER YEAR.
Source Class
Metropolitan Area
New York-New Jersey 1$ Washington 14 St. Louis 15 Los Angeles IS
1966 1966-66 1963 1966
Tons Percent Tons Percent Tons Percent
Fire! combustionPower generation
CoalAnthraciteBituminous
Fuel OilDistillateResidual
Natural GasIndustrial
CoalAnthraciteBituminous
Fuel OilDistillateResidual
Natural *GasDomestic
CoalAnthracite_Bituminous
Fuel OilDistillateResidual
Natural GasCommercial and Government
CoalAnthraciteBituminous
Fuel OilDistillateResidual
Natural GasRefuse disposalIncineratorOpen burningTransportationMotor Vehicles
GasolineDiesel
AircraftShippingRailroadsIndustrial ProcessAaphalt BatchingAsphalt Roofing'ent PlantsChMical PlantsCoffee Processing
184,410 68.1 19,280 56.4 86,80040,042 17.8 9,912 28.6 22,40081,722 18.7 22,400
4781,676 13.7 9,890 28.47,698 3.8 22 0.1
19 0.17,698 3.8
727 6888,599 14.5 851 1.0 89,00028,442 10.5 186 0.4 87,9908,022 8.6
16,420 6.7 186 0.49,669 4.1 182 0.5 6881,479 0.6 28 0.18,090 8.6 169 0.5
688 84 0.1 42841,078 17.8 8,166 9.1 19,90017,767 7.7 786 2.1 18,87316,561 7.2 686 2.01,206 0.6 60 0.1
21,680 9.8 1,889 6.8 67116,826 6.6 1,164 3.36,264 2.7. 686 2.01,726 0.7 692 1.7 864.
19,696 8.6 5,851 16.8 5,6008,189 8.6 8,891 11.2 6,4604,482 1.9 163 0.48,707 1.6 3,788 10.7
10,894 4.7 1,814 6.2 848,281 1.4 661 1.97,618 3.8 1,168 8.8
668 146 0.4 2741,784 18.0 8,165 28.4 15,800
1,70014,100
86,245 (16.2 6,246 18.0 7,10088,761 14.6 6,678 16.3. 4,70022,680 9.8 4,081 11.6 4,10011,181 4.8 1,64'i 4.7 600
410 1.2 2111,484 0.6 670
167 0.5 1,50019,914 8.6 1,110 8.2 87,600
198NA
Coke Plant Not reportedGlass and Frit . Not reportedGrain Industry
68.916.216.2
26.625.8
0.5
0.818.512.8
0.6
0.28.7 Included with3.7 domestic
Tons Percent
8,680 18.84,826 10.6
780 1.6
2,425 6.6
10.71.29.64.88.22.80.40.1.
0.61.0
26.40.1
8,600 2.4
865 0.8865 0.8
21,586 47.017,155 87.516,426 86.9
780 1.64,016 8.8
865 b 0.8
18,866 88.6365 0.8
1,095 2.4No plants
NA 2,920 6.888 Not reported
Not reported 78 No plantsNot reported '' NA 780 1.6
6,696 4.5 Not reportedflee footnotes at end of table.
12
Table 1-1 (continued).-EMISSION INVENTORY OF PARTICULATE MATERIAL, TONS PER YEAR.
Metropolitan Area
New York-Source Class New Jersey 11 Washington u St. Louis 15 Los Angeles 16
1966 1965-66 1963 1966
Tons Percent Tons Percent Tons Percent Tons Percent
MetalsFerrousNonferrous
Solvent UsesSulfuric Acid MfgSuperphosphate MfgOther
Total
12,43312,392
41NA19243
14,063
8.38.3
0.10.29'. 6
2,920 6.41,460 3.21,460 8.26,470 11.9
Not reportedNo plants
366 0.8
231,308 100.0. 34,790 100.1 147,400 100.0 44,346 100.0
Both aircraft and shipping. Includes chemical plant emissions of solvents.Both shipping and railroads. NA Not available.
Table 1-2.-SUSPENDED PARTICLE CONCENTRATIONS (GEOMETRIC MEAN. OF CENTER CITY STA-TION) IN URBAN AREAS, 1961 TO 1965.
Standard metropolitan statistical areaTotal Benzene-soluble
suspended particles organic particles
pg/m, Rank pg/m Rank
Chattanooga 180 1 14.6 2Chicago-Gary-Hammond-East Chicago 177 2 9.6 19.6Philadelphia 170 3 10.7 12.6St. Louis 168 4 12.8 4Canton 166 6 12.7 6Pittsburgh 163 6 10.7 12.6Indianapolis 168 7 12.6 6Wilmington 154 8 10.2 16Louisville 162 9 9.6.. 18Youngstown 148 10 10.5 14Denver 147 11 11.7 8.6Los Angeles-Long Beach 146.6 12 16.6 1Detroit 148 13 8.4 28Baltimore 141 . 14.6 11.0 10 ''Birmingham 141 14.6 10.9 11Kansas City 140 16.6 8.9 28York 140 16.5 8.1 84New York-Jersey City-Newark-Passaic-Patterson-Clifton 186 18 10.1 16Akron 184 20 8.8 30.6Boston 184 20 11.7 8.6Cleveland 184 20 .8.8 80.6Cincinnati 188 22.6 8.8 26Milwaukee 188 22.6 7.4 42Grand Rapids 181 24 7.2 44.6Nashville 128 26 11.9 7Syracuse 127 26 9.3 28Buffalo. 126 27.6 6.0 66Reading 126 27.6 8.8 26Dayton 128 29 7.6 40.6Allentown-Bethlehem-Easton 120.6 80 6.8 60Columbus 118 81.6 7.6 40.6Memphis 118 31.6 7.6 89
13
-.1.111-
Table 1-2 (continued). - SUSPENDED. PARTICLE CONCENTRATIONS (GEOMETRIC MEAN OF CENTERCITY STATION) IN URBAN AREAS, 1961 TO 1965.
Standard metropolitan statistical areaTotal
suspended particlesBenzene-solubleorganic particles
Pg/M 1 Rank 14g/m1 Rank
Portland (Oreg.) 108 34 9.5 19.5Providence 108 34 17.7 38Lancaster 108 34 6.8 50San Jose 105 36.5 14.0 3Toledo 105 36.5 5.6 58Hartford 104 38.5 7.1 46Washington 104 38.5 9.4 21Rochester 103 40 6.1 55Utica-Rome 102 41 7.0 47Houston 101 42 6.8 50Dallas 99 43 8.8 25Atlanta 98 44.5 7.8 36 5Richmond 98 44.5 8.3 30 5New Haven 97 46 7.3 43Wichita 96 47 5.2 60Bridgeport 93 50 7.2 - 44 5Flint 93 50 5.3 59Fort Worth 93 50 7.8 36.5New Orleans 93 50 9.7 17Worcester 93 50 8.2 33Albany-Schenectady-Troy 91.5 53 6.6 52Minneapolis-St. Paul 90 54 6.5 53San Diego 8E" 55 8.5 27San Francisco-Oaldand EO 56 8.0 35Seattle 77 57 8.3 30.5Springfield-Holyoke 70 58 7.0 47.5Greensboro-High Point 60 59 6.3 54Miami 58 60 5.7 57
out the United States. For the most part,measurements were taken at a single sam-pling station in the downtown area of thecity.
Based on ten years of sampling at ap-proximately 370 sites, the highest seasonalaverage will exceed the annual mean by 15to 20 percent. Seasonal averages for thehigh 2 percent of the sites exceeded the an-nual mean by 50 percent and the lowest 2percent exceeded the annual mean by about5 percent. Individual 24-hour maximumsample concentrations vary widely from theannual mean, and on the average this vari-ation is from 280 to 300 percent. Variationsas high as 700 percent of the annual meanare found for the high two percent of thesamples. Sunday and holiday data are us-ually 15 to 20 percent below weekday con-centrations. Table 1-3 shows the relationof population class of urban areas to particle
14:
concentration for the period 1958-1967,while Table 1-4 shows the frequency distri-bution of particle concentration in nonurbanareas for the same period.
Particle concentrations in air have bothdiurnal and annual (seasonal) cycles whichfor most cities are generally predictable inshape. A city with cold winters will experi-ence a seasonal maximum in midwinter asa result of increased fuel use for space heat-ing. A daily maximum in the morning,probably between 6 and 8 o'clock, usually re-lates to a combination of meteorological fac-tors and an increase in the strength ofsources of particulates, including the auto-mobile traffic.
A reflection of the effect of the strength ofvarious sources can also be seen in the pre-viously mentioned lower weekend and holi-day versus weekday concentrations.
. In cities where photochemical pollution
Table 1-3. DISTRIBUTION OF SELECTED CITIES BY POPULATIONCLASS AND PARTICLE CONCENTRATION, 1957 TO 1967.
(Avg. particle concentration pg/ms)
Population class <4040to59
60to79
80to99
100to119
120to189
140to
159
160to
179
180to
199>200
Totalcities
in table
Totalcities
in U.S.A.
>8 million 1 1 2 21-8 million 2 1 3 3
0.7-1 million 1 2 4400-700,000 4 5 6 1 1 1 18 19100-400,000 8 7 80 24 17 12 3 2 1 99 10050-100,000 2 20 28 16 12 6 5 1 3 93 18026-50,000 5 24 12 12 10 2 1 2 8 7110-25,000 7 18 19 9 5 2 8 1 64 5,458
<10,000 1 5 7 15 11 2 1 2 44
Total urban 1 22 77 108 79 52 81 16 8 7 401
Incorporated and unincorporated areas with population over 2,500.
Table 1-4.DISTRIBUTION OF SELECTED NON-URBAN MONITORING SITES BY CATEGORYOF URBAN PROXIMITY, 1957 TO 1967.n
CategoryAverage particle
concentrations, agfins Total
<20 20-89 40-59 60-79
Near urbanIntermediate bRemote 4
1
55
86
1 5119
Totalnonurban 4 11 9 1 25
Near urbanalthough located in unsettled areas,pollutant levels at these stations clearly indicate in-fluence from nearby urban areas. All of these stationsare located near the northeast coast "population cor-ridor."
b Intermediatedistant from large urban centers,some saricultural activity, pollutant levels suggest thatsome influence from human activity is possible.
Remoteminimum of human activity, negligibleagriculture, sites are frequently in state or nationalforest preserve or park areas.
predominates, the maximum in concentra-tion of particles in the range from 0.1p to 1i4may come around noon, after the sun hashad an opportunity to cause photochemicalreaction. Under these conditions, the highestconcentration of particles below 0.1p willcome earlier, and there may be no clear trendfor larger particles.
The above concentrations generally relate
to samples taken in the center-city commer-cial district. This portion of the communitywill generally not show annual average con-centrations as high as those found in variousindustrial areas; however, they are amongthe higher area concentrations in a com-munity. Annual concentrations in nearbysuburban residential areas generally will beabout one-half of that found in center city.
Particulate air pollution is not onlysource- and location-dependent but is alsoa function of meteorological factors causinga variation in the natural ventilation of acommunity. Air pollution episodes are char-acterized by minimum natural ventilation,and particulate concentrations at such timesmay rise dramatically as indicated by thefollowing examples: during the November-December, 1962, episode in the EasternUnited States, particulate concentrations inseveral communities rose to two-to-threetimes normal; " during the Thanksgiving1966 episode, again in the Eastern UnitedStates, particulate concentrations increasedby about a factor of two over mean autumnlevels. In fact, maximum citywide averageconcentrations in Philadelphia, Worcester,and Boston exceeded maximum concentra-tions recorded for an autumn period since1961 at the National Air Surveillance Net-'work (NASN) stations."
Table 1-5 gives concentrations of certainspecific contaminants found in total sus-
15
Vi7
Table. 1-5. ARITHMETIC MEAN AND MAXIMUM URBAN PARTICULATE CONCENTRATIONS IN THEUNITED STATES, BIWEEKLYY SAMPLINGS,. 1960 TO 1965.21
Pollutant ;. Number ofstations
Concentrations pg/ms
Arith. average Maximum
Suspended particulatesFractions:
Benzene-soluble organics
291
218
105
6.8
1254
(b)Nitrates 96 2.6 39.7Sulfates 96 10.6 101.2Ammonium 56 1.3 75.5Antimony_ 35 0.001 0.160Arsenic 133 0.02 (b)Beryllium 100 <0.0005 0.010Bismuth 35 <0.0005 0.064Cadmium 35 0.002 0.420Chromium 103 0.015 0.330Cobalt 35 <0.0005 0.060Copper 103 0.09 10.00Iron 104 1.58 22.00Lead 104 0.79 8.60Manganese 108 0.10 9.98Molybdenum 35 <0.005 0.78Nickel 103 0.034 0.460Tin 85 0.02 0.50Titanium 104 0.04 1.10Vanadium 99 0.050 2.200Zinc 99 0.67 58.00Gross beta radioactivity 323 (0.8 pci/ms) (12.4 pCi /m')
Arithmetic averages are presented to permit comparable expression of averages derived from quarterly com-posite samples; as such they are not directly comparable to geometric means calculated for previous years' data. Thegeometric mean for all urban stations during 1964-65 was 90 pg/ms, for the nonurban stations, 28 pg/ms.
b No individual sample analyses performed.
pended particulate matter. Certain sub-frac-tional contaminants found in total particu-lates may be related to community param-eters; for example, average ambient vana-dium concentrations correlate well with thekind of residual oil used, iron and manganesecorrelate and are attributed to their jointemission from ferromanganese blast fur-.naces, and annual gasoline sales correspondwith the average lead fraction of suspendedparticulates. Similarly, sulfates correlatewith particulates in those communities whichderive large amounts of energy from thehigher sulfurous fuels."
2. DustfallDustfall is the usual index of particles in
the size range greater. than 10p, and it hasmainly been reported in short tons persquare mile per month, arrived at by extra-polation from a jar a few inches in diam-eter to a square mile. Metric units are pref-
16
erable and the current trend is clearly intheir favor. Typical values for cities are0.35 to 3.5 mg /cm= -month (10 to 100 tons/mile'- month), While values approaching 70mg /cm -month (2000 tons/mile2-month) havebeen measured near especially offensivesources.
A search for scientific interpretations orcorrelations of dustfall data has been unsuc-cessful. There is no question that, within agiven city, dustfall tends to increase withthe intensity of human activity. Further-more, dusifall measurements are certainlyvaluable in obtaining evidence against majorsources of dust. However, trying to extractdetailed information from small fluctuationsin dustfall appears to be an exercise in fu-tility. Dustfall is complex, being affected bythe, number of unvegetated vacant lots, ve-hicular traffic, uncontrolled heavy industry,and wind velocity. Dustiness of the environ-
t
ment is an obvious nuisance and a compo-nent of the economic cost of pollution.
F. SAMPLING AND ANALYSIS OFATMOSPHERIC PARTICULATE
MATTER
I. Particles Larger Than 10pParticles larger than 10p exist in the at-
mosphere in very low numerical concentra-tions. The high concentrations that aresometimes found in ducts or in work spacesare the province of industrial hygiene andare not considered here.
Since the largest particles have appre-ciable settling velocities and impact readilyat low velocities, they are usually determinedgravimetrically following collection by depo-sition in a dustfall jar." Although a cylin-drical jar .might be expected to collect theequivalent of the dust content of an air col-umn of its own diameter extending to thetop of the atmosphere, in fact the aerody-namic effects of the jar edges, of the mount-.ing brackets for the jar, and of adjacentstructures tend to complicate the collectionpattern. Only relative significance may beattached to the resulting data, and only thenif conditions are carefully standardized."-2(There is a legend of a city which decreasedits reported dustfall by half in a single yearby changing the height of its dustfall jarsfrom 8 to 20 feet above ground level.) Thereis no definitive study of the effect on meas-ured dustfall of the height of the collectorabove ground.
Gruber " has successfully used an adhe-sive coating on the outside of cylindrical con-tainers to ascertain the wind direction corre-sponding to maximum dust content of theair. This often permits identification of ma-jor dust sources. Evaluation is visual. Euro-pean practice favors flat adhesive surfacesplaced horizontally as dust collectors." Theadvantages are not apparent, and analogousstudies using greased microscope slides forpollen collection have shown them to behighly variable in collection efficiency."
Cyclonic collectors have been employed incombination with high-volume samplers forthe selective sampling of particles." Whilesuch collectors can remove virtually all parti-'des above 511, they also remove a significant
amount of smaller particles. During an in-vestigation of atmospheric protein, a smallcyclone separator was used ahead of a high-volume sampler. Particles exhausted throughthe cyclone outlet were collected on a filter ofthe high-volume sampler. The samples col-lected on the filter of the combination unitaveraged about one-half the weight of thosecollected at the same time on the filter of ahigh-volume sampler with no cyclone at-tached.
A few studies 32-34 have used long horizon-tal tunnels as fractional elutriators to deter-mine particle size distributions. The elutria-tor acts as a prefilter for the removal oflarger-sized particles in a manner similar tothe cyclone high-volume sampler combina-tion. Both the cyclone and the elutriator, op-erating on aerodynamic principles, have agraded selectivity (Figure 1-6) rather thana sharp cut-off point at a specific particle size.The size range of the particles which pene-trate the elutriator but are retained on thefilter at the outlet duct depends on the air-flow rate through the system (Figure 1-6).
Other methods for the selective removal oflarger (nonrespirable) particles have beendescribed by Lippmann and Harris 38 and byRoesler."
The first stag 3 of most cascade impactors 38collects particles larger than about 5 to 10p.Since, except in very dusty atmospheres, themass mean diameter' is smaller than this, col-lections on the first stage will be meager un-less the sampling time is set specifically to
2 3 4
AERODYNAMIC SIZE. p
FIGURE 1-0. Horizontal Elutriator Cut-off Charac-teristics.' (This graph shows that the elutriatorcollects all particles larger than 314 diameterwhen operated at 10 cfm, but at 50 cfm some par-ticles as large as 7µ diameter escape.)
Ati.1
17
give ample material. Adhesion of such largeparticles is poor (Section B-1), so an ad-hesive may be necessary to avoid bounce-offor reentrainment.
A variation is a single-stage impactor withsize discrimination developed by Dessens."He used a coarse slit followed by a shapedchannel to induce turbulent deposition ofparticles along a microscope slide with asize gradation from larger to smaller.
It appears, therefore, that no presentlyused technique for the concentration meas-urement of particles larger than about 10µ issuperior to a properly installed dustfall jar;this method is also the least expensive. How-ever, the jar lacks time resolution since itmust usually be exposed for two weeks to amonth to obtain a significant sample. Dust-fall jars should be more widely standardized,and more study is needed of alternativemeans of sampling the largest particles in theatmosphere. Chapter 11 shows some correla-tions of health effects with air pollution, us-ing dustfall as an index of air pollution.
Any collection technique can provide asample for subsequent analysis, although theadhesives used in many of the methods de-
250
scribed can, unless carefully chosen, inter-fere severely with characterization of theparticles. The standard techniques used toanalyze dustfall samples generally revealwhich elements are somewhere in the samplewithout giving any information as to whichparticles contain which elements or whatcompounds these elements represent. Never-theless, such general chemical compositiondata are often helpful. One simple type ofchemical characterization which gives thissort of information for particles larger than10p, is morphological identification under themicroscope. Although this may be applied tosmaller particles as well, it is most effectivein the largest size range. McCrone 4° haspublished a photomicrographic atlas of dustcomponents which should permit recognitionof up to 90 percent of the particles above 10µin a typical urban sample. In the hands of anexperienced microscopist, this technique isone of the most potent tools in dust analysis.X-ray diffraction techniques will identifychemical compounds present rather thanmerely the elements.
Dustf all levels have decreased in mostcities (Figure 1-7) and there is a trend
200
150
100
so
0
**** 0,....0".*".....4%. 2''TA T7:.-----__ PHILADELPHIAPITTSBURGH
ems ""44416.....Alb.- "Lt.
4".".. CINCINNATI"'" eft.
-. am. Mu,
10
g
6
4
1950 1955 1960 1965
FIGURE 1-7. Dustfall. Data for Six Cities. (This graph is from a U.S. Government publication, butoriginal source of the data is unknown.)
ve
18
the
toward abandoning routine dustfall measure-ments, as they may no longer be indicative ofpollution levels. This viewpoint is defensible,although, since excessive dustfall is one ofthe most noticeable nuisances consequentupon air pollution, there is public pressure toabate high dust emissions (Chapter 7).
2. Particles 0.1tt to 10/4A single group of sampling and analysis
methods generally serves for the size rangefrom 0.1t to 10 &. This size range includesboth the bulk of the particulate mass. and alarge fraction of the numbers. The prepon-derant optical effects also arise from parti-cles in this portion of the size spectrum, andmost of the estimation methods not involvingcollection are optical. Collection and analysistechniques in this size range have been- re-viewed by Lodge " 42 and discussed in twochapters of the 1968 treatise, Air Pollution,edited by Stern.49 44
The simplest o.-.' Pl technique involves useof a photometer vIdoped in its present formby Volz 45 for determining air turbidity. Asimple photocell is pointed at the sun througha series of small apertures and a glass filterpeaking at a wavelength of 500 ,z. An attachedsight and spirit level allow measurement ofsun angle, which corrects the reading for airlayer thickness along the path between theinstrument and the sun. A nomogram maythen be used to obtain the turbidity coeiffi-cient. Greater accuracy, if warranted, maybe achieved by using a computer; a simpleprogram has been developed for the calcula-tion." McCormick'; found that turbiditymeasurements from the bottom and fromthe top of a high building gave, by difference,a reasonable estimate of the concentration ofthe intervening particulate matter. This isthe cheapest and simplest technique, althoughit cannot measure continuously nor can it beused at night or during cloudy weather.
Next in complexity is the "nephelmneter"described by Charlson." This device meas-ures light scattered by particles suspended ina defined volume of air. It is illOminated by aflash tube placed so that nearly the total solidangle from full forward to direct back-scat-tering occurs. Integral scattering is recordedand, in the absence of a powerful nearby
particle source, is very nearly a linear func-tion of mass concentration. A disadvantageof the method is that a constant particle-sizedistribution and composition must be as-sumed.
Other light-scattering instruments includetotal forward-scattering and right-angle-scattering photometers as well as instru-ments which count and size individual parti-cles.49 The latter consist of:
1. A sampling system which dilutes thesample stream with purified air untilonly one particle at a time is likely tobe in the sensitive portion of the de-vice,
2. a light source and optics to illuminatea small volume (a few mm3 at most)at a defined angle,
3. a phototube (usually a multiplier)sensitive enough to detect the indi-vidual flashes of light as particlespass the illuminated volume, and
4. a pulse height analyzer and countingelectronics.
A number of other principles for size an-alysis of particles without collection weresurveyed during World War H and the im-mediate postwar years, but none seem tohave warranted commercial exploitation ex-cept one device to measure mobility in anelectric field. This latter technique is moreapplicable to smaller particles and will bediscussed in that connection (see SectionG-3) .
Cascade impactors 39 have been found tobe useful devices for simultaneously collect-ing and clasilfying particles throughout mostof this size range, thereby yielding consider-able information 99-33 on the urban aerosolsize distribution of selected chemical com-ponents including sulfate, lead, and othermetals. Similar information has been ob-tained by use of a helical-channel centri-fuge 54-55 as a classifier.
Goetz " has described a single-stage mov-Eng-slide impactor with some novel features.It is part of a system which includes mirror-surfaced collecting slides and incident dark-field microphotometry which is particularlywell adapted to physical characterization ofparticles from roughly 0.21.4 to 2tt. Informa-
. 19
tion on coalescence tendency and heat labilityis easily obtained.
Spurny 58 has studied the application ofrecently developed filter material to particleresearch. The filter is a plane film of polycar-bonate which is exposed to fission fragmentsand then treated to remove the radiationdamage. A number of pore sizes are avail-able; the pores are uniform, straight, and cir-cular in cross section. The plane upper sur-face is ideal for both optical and electron mi-croscopy ( the latter after replication), andthe filtration characteristics are excellent.The uniformity of the material commends itsuse for gravimetric purposes and for "smokeshade" determination. The only evident dis-advantage at the moment is its price.
Frank and Lodge 59 have described the useof electron microscopy for morphologicalidentification of several species of particlessmaller than 1p. Although the technique isnot so broadly applicable as is optical mi-croscopy of dusts, it may permit some an-alyses, including the identification of sulfuricacid droplets below 1p.
In view of the extensive literature involv-ing filter tape and high-volume samplers,some further discussion of these devices is inorder, especially since air quality criteriamust ultimately relate to accurate measure-ments. Both samplers are inexpensive anddurable, and both provide data which havestringent limitations that are not alwaysunderstood.
a. Tape Samplers for Suspended ParticulateMatterThe tape sampler most widely used in the
United States has been the AISI (AmericanIron and Steel Institute) sampler developedby Hemeon and his colleagues.6° Other ver-sions exist, but all are alike in function. Aseries of portions of filter paper, usually suc-cessive areas of a paper tape, are positionedso as to be clamped between an intake tubeand a vacuum connection. Air is drawnthrough the filter for a selected time, usuallyone to four hours, and a new portion of tapeis then moved into position and sampling isresumed.
The fundamental basis of evaluating sam-ples is optical, although a few nonoptical
20
methods have been studied. The visual colorof the spots may be compared with a stand-ard gray scale. The reflectance may be meas-ured pintom :;.:ically. The transmittance oflight through both filter and deposit may becompared with transmittance through a cleanportion of the filter. Visual and reflectancemeasurements determine the blackness of thedeposit, while transmittance measures afunction of all partfeles collected, and undersome circumstances measurements made bythe two techniques may not be identical. Forexample, a gram of magnesium oxide smokecollected in a single spot would not be visiblygray and might even increase reflectance, butwould transmit no light at all. Urban particu-late matter is not, however, pure magnesiumoxide, and, in fact, the three measures (vis-ual, reflectance, and transmittance) gener-ally correlate fairly well in the short run.Over longer periods, the introduction of newsources and the removal of old ones may beexpected to change the cemposition of theparticles enough to cause divergence of thedifferent techniques. For example, if a resi-dential area abruptly converts from coalheating to gas, the virtual disappearance ofsoot will have an enormous effect on reflect-ance which may not appear so strikingly intransmittance.
Transmittance is by no means a uniquefunction of the total concentration of partic-ulate matter. Stalker et al." compared trans-mittance and particle concentrations in dif-ferent parts of Nashville, Tennessee. Theslopes of the regression lines varied by a fac-tor greater than three, and at some locations1:0 correlations appeared to exist between thetwo measurements.
Additional complications arise in threeways. First, none of the methods of measure-ment exhibit a linear relationship betweenthe quantity determined and the number ofparticles collected. Reflectance changes willdepend on whether later deposits are re-tained on the surface of, or penetrate deeplyinto, the layers first deposited. Measurementsof transmittance are similarly dependent onwhether an added increment simply addsthickness to the collected deposit or fills poresand gaps, thus increasing the bulk densitybut not the thickness of the layer.
Second, the rate of sampling is not con-stant but depends on the amount of materialalready collected and the structure of thedeposit." Hence the assumption of a constantsampling rate will be seriously in error, es-pecially for heavy deposits. Averaging initialand final sampling rates, or recording thesampling rate continuously, represent im-provements at the cost of greatly increasedattention to the instrument, or of increasedcomplexity and expense.
Third, reflectance methods lose all discrim-ination beyond a certain deposit density.Once the filter is covered with particulatematter, only the exposed. surface of the de-posit affects the reflectance; the reflectancethen become a measure of the composition,but not the amount of material collected. Thisproblem is recognized, but not solved, in aproposed European standard method."
Transmittance, which is most widely,meas-ured in the United States, is normally con-verted into units of coh's per thousand linearfeet of air passing through the filter. Cohstands for "coefficient of haze." A coh unit isdefined as that quantity of light-scatteringsolids (on the filter) which produces an opti-cal density equivalent of 0.01 when measuredby light transmission. Optical density is de-fined as the common (decadic) logarithm ofthe opacity (inverse of fractional transmis-sion). Thus if one-fifth of the incident lightis transmitted through the paper, as com-pared with clean paper, the opacity is five.A coh measurement is routinely reduced tocoh per 1,000 linear feet of air passingthrough the filter tape by dividing the unre-duced coh value by the number of thousandsof feet actually drawn in the test.
For reflectance, a RUDS test is made bymeasuring the percentage reflectance of thefilter tape and similarly reducing the meas-urement to 1,000 linear feet of air. Reflect-ance of clean paper tape is the referencestandard, set at 100 on the reflectometer.RUDS is an acronym for "reflectance unit ofdirt shade."
Reflectance measurements are used in vari-ous European countries for calculating am-bient air concentrations of "smoke" or "darksuspended matter." The darkness of thefilter stain is not considered proportional to
total particle concentration in the air but tothe concentration of "dark suspended mat-ter" resulting primarily from combustion.The darkness of the stain, as measured by areflectometer, is converted to surface concen-tration of smoke by means of a calibrationcurve. The derived surface concentration isthen translated into an ambient concentra-tion using the relationship:
SAC= (1-2)
Vwhere C = the concentration of smoke in the
air (µg /m3),S = the derived surface concentration
(pg/cm3),A = the area of the filter stain (cm2),
andV = the volume of air sampled (m3).
Experimental work on the form of thecalibration curve for deriving surface con-centrations has been carried out in France,the Netherlands, and the United Kingdom.
Working Party on Methods of Measur-ing Air Pollution and Survey Techniques ofthe Organization for Economic Cooperationand Development has proposed a StandardInternational Calibration Curve (the meanof the curves developed in the three countrieslisted above) as well as a standard samplingand measurement procedure."
The use of the conversion curves to makeinternational comparisons is potentially dan-gerous. The method has the disadvantage ofcredibility; that is, it is too easy to overlookthe arbitrary nature of the units, and to be-lieve that actual airborne particle concen-trations have been measured. This is of con-cern for those areas of the United States forwhich air quality standards already exist; inmost cases the standards include separatevalues for "airborne particulate matter" ex-pressed in gravimetric units, and for "atmos-pheric soiling" determined by transmittanceor reflectance measurements on deposits ofthe sort described here.
For. many purposes, the InternationalStandard Calibration Curve will be found in-convenient. It is the empirical product of acomplex physical phenomenon (light absorp-tion and scattering) and an arbitrary instru-ment response: The curve is not a
!3321
matical one, and hence computer reduction ofdata is made awkward.
Still other conversion formulae have beensuggested by Kemeny " in South Africa, byEllison 68- in England, and by Sullivan 66 inAustralia. These workers, following Clark,"have attempted to convert their readingsmathematically into units of milligrams percubic meter of "smoke" in the air. As Sander-son and Katz 68 have correctly stated, "Thereis considerable doubt whether a truly satis-factory expression exists for the translationof optical density readings into units relatedto smoke and haze concentrations." The re-sults of Stalker et aL," previously mentioned,suggest that this may be an understatement.The method yields only an index of and not ameasurement of absolute concentrations ofsuspended particulate matter.
Notwithstanding its limitations, the tapesampler is cheap, simple, and rugged, and itwill certainly continue to be used. It should,however, be used with the knowledge that itsmeasurements, in whitever units, are arbi-trary and .artificial and without absolutemeaning. Their relative values can be usefulif the samplers, as well as their locations,their installation, and the technique of meas-urement, are rigorously standardized. Fur-thermore, it must be kept in mind that long-term trends may reflect changes in com-position as well as in amount of airborneparticles.
b. High-Volume Samplers for SuspendedParticulate MatterThe . original high-volume sampler con-
sisted of the motor and blower of a tank-typevacuum cleaner, suitably enclosed and fittedwith a holder for flat filter paper in place ofa dust bag. Present versions are more re-fined, but little different in. concept. The useof a blower necessitates a filter of large areasand low air resistance, and also makes thesampling rate very dependent on the mass ofmaterial collected.
Current samplers 30 are generally exposedinside a case which places the filter surfacehorizontal, facing upward, under a roofwhich keeps out rain and snow, and generallyprevents collection of particles larger thanabout 1001A. Filters are felts of glass or syn-
22
thetic organic fiber. Since the fibers are sub-stantially less than 1K in diameter, these fil-ters are highly efficient despite their openstructure and consequent low resistance toairflow. Samples are normally collected for24 hours and sampling rates are measured atthe beginning and end of the period.
Since the filters are weighed before use, itis possible to determine the weight of col-lected material if one standardizes the weigh-ing conditions, optimally at 25°C and at rela-tive humidities below 50 percent. Thereafter,samples may be extracted, heated, or in-cinerated, and determination can be made oforganic content, carbon, minerals or anyother .suitable and/or interesting fraction,element, or substance. The collected sampleis the particulate content of approximately2,000 m3 of air, and is large enough fornearly any sort of analysis, although caremust be used in interpreting the data. Therearea few studies on interactions between col-lected species, loss through volatilization, andsimilar problems. The performance charac-teristics of high-volume samplers today arequite well understood, thot/Eik reactions onsampler filters are not.
Many analyses are plagued by the lack of auniversally applicable filter material. Glassfiber filters are convenient for determiningtotal particle concentration. However, thevery fine glass fibers are water and acid sol-uble, and the glass contains significantamounts of a large number of metals, as wellas sulfate, silicate, and other anions. ,Henceinorganic analyses are performed over abackground from the filter which. is by nomeans constant. Polystyrene fiber filters canbe made extremely low in inorganic content,,but are virtually useless for organic analysis.Membrane filters .are very useful in specialapplications, e.g., when alkaline metals are tobe determined.
Suspended particle concentrations, deter-mined by high-volume samplers in urbanareas, are shown in Table 1-2. The columnlisting "Benzene soluble organic particles" isa measure of the organic particulate matterin the total sample. Much of this material isderived from the incomplete combustion offuels. The data on organics may be furtheranalyzed for polycyclic aromatic hydrocarbon
Yr
content; a possible significance of these com-pounds in carcinogenesis is discused in Chap-ter 10.
3. Particles Smaller Than 0.1p
Several techniques have been used sys-tematically for the characterization of parti-cles smaller than 0.1p..
1. Saturation of the air and subsequentrapid expansion to cause a high su-persaturation: the resulting dropletcount is assumed equal to the totalparticle concentration. Successivelysmaller degrees of supersaturationpresumably activate only larger parti-cles to act as nuclei. Size spectra maybe generated in this way, although theresults do not necessarily agree withthose of other methods. Most of theavailable data were obtained by thistechnique."
2. Passage of the air through a longnarrow channel: The smallest parti-cles will be removed most rapidly bydiffusion, and the extend of the ef-fect can be calculated." Differentialcondensation nuclei counts after dif-ferent diffusion lengths permit deter-mination of a size spectrum.
3. Measurement of the mobility ofcharged particles in an electric field:It is necessary to assume or to com:pute the efficiency of electrical charg-ing of these smallest particles to de-rive numbers and effective sizes. Orrand his coworkers " used this methodto study changes in the size of hygro-scopic particles with relative humid-ity, and 'Whitby 72 has set up a facilityfor obtaining count-size distributionsof particles in air, using a series ofinstruments with overlapping ranges.
4. Electron microscopic techniques havebeen used to obtain particle counts aswell as' information on the size andMorphology of these small particles.
Of these methods only the electrical mobil-ity separator has been used 71 for chemicalcharacterization of particles below 0.1p, butlittle analytical information is now available.
The electron microscopic methods of Frankand Lodge," and the earlier work of Tuftsand Lodge," provide some insight into thechemical composition of the particles, al-though even in the most favorable cases, theauthors were able to account for the com-position of less than half of the particlesseen.
G. SIZE, CHEMICAL COMPOSITION, ANDSOURCE STRENGTHS OF PARTICULATE
MATTER FROM SELECTED EMISSIONSOURCES
A listing of source strengths is given inTable 1-6. Composition of particles and,where available, data on particle size distri-bution from various sources follow.
1. Open-Hearth Furnaces
a. Chemical Composition
Analysis" of particulate emissions from a200-ton oxygen-lanced open-hearth furnace,a composite sample for all process stages, in-dicates the following chemical composition:
Compound PercentFe203 89.1Fe0 1.9Si02 0.9A103 0.5Mn0 0.6Alkalis 1.4P205 0.5S 0.4
Fluorides may be present in open-hearth fur-nace particulate emissions if fluorspar fluxesor fluoride-containing ores are used. 'Whilefluoride emissions are generally insignificant,problems have been reported in the vicinityof at least one plant which uses fluorsparfluxes and one which uses an ore with a highfluoride content."
b. Particle SizeBy number, the majority of particles emit-
ted by an open-hearth furnace are below0.1A in diameter." Size analysis " of a com-posite sample over the entire hearthcated the following distribution:
28
Diameter Weight percent(1z) less than stated size
2 205 46
10 6820 8540 93
2. Incinerationa. Chemical Composition
Analysis of emissions from municipal in-
cinerators in Los Angeles " indicated 20 per-cent by weight of the discharge to be con-densable and approximately 5 to 15 percentof the condensate to be sulfuric acid. Theremaining 80 percent was particulate mat-ter containing silicon, lead, aluminum, cal-cium, iron, and traces of other eliments.
Particulate samples from the stack effluentof municipal incinerators in Milwaukee,"asked and subjected to spectographic and
Table 1-6.EMISSION FACTORS FOR SELECTED CATEGORIES OF UNCONTROLLED SOURCES OF *-PARTICULATES.
Emission source Emission factor
Natural gas combustion:Power plantsIndustrial boilers
. Domestic and commercial furnaces
Distillate oil combustion:Industrial and commercial furnacesDomestic furnaces
Residual oil combustion:Power plantsIndustrial and commercial furnaces
Coal combustion:Cyclone furnacesOther pulverized coal-fired furnacesSpreader stokersOther stokers
Incineration:Municipal incinerator (multiple chamber)Commercial incinerator (multiple chamber)Commercial incinerator (single chamber)Flue-fed incineratorDomestic incinerator (gas-fired)Open burning of municipal refuse
Motor vehicles:Gasoline-powered enginesDiesel-powered engines
Grey iron cupola furnaces
Cement manufacturing
Kraft pulp mills:Smelt tankLime kilnRecovery furnaces b
Sulfuric acid manufacturing
Steel manufacturing:Open-hearth furnacesElectric arc furnaces
15 lb/million ft' of gas burned18 lb/million ft' of gas burned19 lb/million fts of gas burned
15 lb/thousand gallons of oil burned8'lb/thousand gallons of oil burned
10 lb/thousand gallons of oil burned23 lb/thousand gallons of oil burned
2X (ash percent) lb/ton of coal burned13-17X (ash percent) lb/ton of coal burned13X (Ltsh percent) lb/ton of coal burned2-5X (ash percent) lb/ton of coal burned
17 lb/ton of refuse burned3 lb/ton of refuse burned
10 lb/ton of refuse burned28 lb/ton of refuse burned15 lb/ton of refuse burned16 lb/ton of refuse burned
12 lb/thotisand gallons of gasoline burned110 lb/thousand gallons of diesel fuel burned
17.4 lb/ton of metal charged
38 lb/barrel of cement produced
20 lb/ton of dried pulp produced94 lb/ton of dried pulp produced
150 lb/ton of dried pulp produced0.3-7.5 lb. acid mist/ton of acid produced
1.5-20 lb/ton of steel produced15 lb/ton of metal charged
a For more detailed data, consult "Control Techniques for Particulate Air Pollutants," U.S. Department ofHealth, Education, and Welfare, Dec. 1968
b With primary stack gas scrubber
24
wet chemistry analysis, had the followingcomposition:
SPECTOGRAPHIC ANALYSISElements reported in percent of (felted material
Element PercentCalcium 10 +Silicon 5 +Sodium 1-10Nickel 1-10Aluminum 1-10Zinc 1-10Magnesium 1-10Titanium 0.5-5.0Iron 0.5-5.0Barium 0.1-1.0
Small amounts (less than 1 percent) of man-ganese, chromium, copper, vanadium, tin, sil-ver, boron, beryllium, and lead were present.
WET CHEMICAL ANALYSISPercent
Phosphorus 1.46SilicatePhosphates 0.88Nitrates 0.62Sulfates 5.0Chlorides 0.02
Analysis of fly ash collected at three NewYork Te incinerators and of that.emitted fromtheir stacks showed the following chemicalcomposition:
Weight percentCollected Emitted
Silicon as Si02 49.5. 36.3Aluminum as ,A1208 22.9 25.7Iron as Fe208- 6.3 7.1Calcium as Ca0 8.8 8.8Magnesium as Mg0 .2.2 2.8Sodium as Na20Potassium as K205 6.0 10.4
Titanium as TiO2 1.3 0.9Sulfur as SO8 3.0 8.0
b. Particle SizeAnalysis of the, particulate emissions from
the Los Angeles municipal incinerators in-dicated 30 percent (by weight) of the par-ticles were less than 5p in diameter. Particlesize analysis of the samples collected at theMilwaukee ?8 incinerators showed the fol-lowing distribution:
Diameter Weight percent(p) less than stated size
5 6.010 20.520 47.230 68.744 89.2
3. Sulfuric Acid Manufacture: ChamberProcess
a. Chemical CompositionAcid mist emissions contain sulfuric acid
and dissolved nitrogen oxides. The nitrogenoxides constitute approximately 10 percentby weight of total acid mist emissions.
b. Particle SizeThe weight percentage of acid mist par-
ticles less than 3p in diameter found in sam-ples from two chamber acid plants, one usingmolten dark sulfur and one using solid sul-fur, were 10.1 percent and 3.5 percent re-spectively.
4. Sulfuric Acid Manufacture: ContactProcess "
a. Chemical Composition.Discharge gases contain sulfuric acid mist
as well as unabsorbed sulfur trioxide, whichconverts to acid mist upon reaching the at-mosphere. Trace amounts of nitrogen ox-ides may arise if the fuel used in the proc-ess contains nitrogenous matter.
b. Particle SizeIn plants where particle size has been de-
termined, the weight percentage of particles3p or less in diameter leaving the absorberunit ahead of any mist recovery equipmentranged from 7.5 percent to 95 percent. Themean percentage was 63.5.
When oleum is produced, the proportionof acid mist particles smaller than 3p in di-ameter increases. In one plant, the percent-age rose from 9.5 percent to 54 percent.
5. Cement Plants
a. Chemical CompositionChemical analysis of the raw kiln feed
dust and the kiln dust from the precipitatoroutlet of portland cement plants in the Le-
25
high Valley, Pennsylvania, region showedthe following composition:
Compound*
Weight percent
Raw kiln Dust fromfeed dust precipitator
(Average for outlet (Averagethree types of threeof cement) samples)
Ca0 40.9CaCO3 75.9SiO, 13.4 18.8A1203 3.7 7.1Fe20, 2.1 9.6Mg0 2.5Na20 1.1K20 7.3Mn0 0.2TiO2 0.1CuO TraceIgnition Loss .... 12.7No determination of sulfur made.
b.. Particle SizeExamples of the distribution of particle
sizes in cement plant raw kiln feed and kilnemissions are indicated below:
Diameter(u)
6050
Raw kiln feed Kiln emissionsweight percent weight percent
less than stated size less than stated sizeRef. 81 Ref. 81as Ref. 1
81.4 97-10073.1 95-100
40 63.8 96.5 85-9530 53..3 92.9 70-9020 41.5 84.6 50-70.10 23.5 56.3 30-555 10.8 15.5 20-402.5 10-35
Average of two samples
6. Motor Vehicles
a. Chemical CompositionParticles contained in vehicle exhaust in-
clude lead compounds, carbon particles, motoroil, and nonvolatile reaction products formedfrom motor oil in the combustion zone.' Thereaction products include high molecularweight olefins, carbonyl compounds (alde-hydes and ketoneS), and free acids. Leadparticles in the exhaustare principally in thefrom of PbC1Br, the wand /3 forms of NII4C1.
'26
2PbC1Br and 2NH4C1. PbC1Br. Particulatesdischarged through the blowby consist al-most entirely of unchanged lubricating oil."
b. Particle SizeAnalysis" of diluted exhaust from automo-
biles operated at crusing conditions showeda particle concentration of 40 to 52pg perliter of exhaust. From 62 to 80 percent of theparticulate mass consisted of particles withaerodynamic diameters below 2µ at unit den-sity. The lead content of particulate emis-sions averaged about 40 percent and ap-peared to be independent of particle size.Measurements 84 with undiluted auto exhaustindicate that about 90 percent by weight ofexhaust lead is contained in particles withdiameters below 0.5p.
7. Fuel Oil Combustiona. Chemical Composition
The probable constituents 85 of fly ash fromoil combustion have been identified as A1203,Al2( SO4)8, CaO, CaSO4, Fe208, Fe2(SO4)8,MgO, MgSO4, NiO, NiSO4 Si02, Na2SO4,NaHSO4, Na2S207, V203, V20V205, ZnO,ZnSO4, Na2CV205, 2Na20 .V205, 3Na20205,2NiO.V205, 3NiO.V205, Fe202705, Fe202V202, Na20V204.5V202 and 5Na2O20411V202.
Analysis " of fly 'ash ,from a plant usingresidual oil .produced Cite; following percent-age composition:
Test A Test BTotal :Aids Total solidsfrom burn- from burn-ing PS 400 ing 4° APIoil (Col- oil (Col-
lected in a lected in aElement laboratory glass
Electrical filter sock`precipitator at 300°F)
at 230°F)(Weight (Weightpercent) percent)
Carbon 58.1° 18.1Ether Soluble 2.3 4.4Ash (900°C) 17.4 51.2Sulfates as SO2 17.5 25.0
(Including H2SO4)Iron as Fe202 3.1 3.7Nickel as Ni0 1.8 13.2Vanadium as V203 .2.5 4.7Silicon as Si02 0.6 9.7Aluminum as A1203 1.6 14.9Sodium as Na20 0.9 3.0
a May include some hydrogen
Less than 1 percent of the following ele-ments or compounds was present: Cl, NO3,Cr02, Co20v BaO, MgO, PbO, CaO, CuO,Ti02, MoO2, B208, Mn02, ZnO, P202, SrO,TiO.
b. Particle Size
A literature survey 81 of the size distribu-tion of particles emitted by large oil-burningunits gave the following results:
SIZE DISTRIBUTION(Percent by number)
OA to 11, /A to 2p, 2p, to Sp 5 + p, Largest size
48.4 28.8 16.7 6.1 15p.64.2 18.8 10.0 7.0 15p.93.5 .3.2 2.0 1.3 20p.94.8 2.2 1.5 1.0 20p.One reference indicated 47 percent, by
weight, was less than 3p. diameter.
8. Combustion of Coal
a. Chemical CompositionThe following ranges in chemical composi-
tion were indicated by analysis of fly ashemissions from a variety of coal combustionunits. The figures are the extreme values
88
Particle Size(p.)
1020406080
100200
found in four investigations, each of whichreports wide ranges also.
CompoundPercentageof fly ash
Carbon, C 0.37-36.2Iron (as Fe03 or Fe,04) 2.0 -26.8Magnesium (as Mg0) 0.06- 4.77Calcium (as Ca0) 0.12-14.73Aluminum (as A1203) 9.81-58.4Sulfur (as SO,) 0.12-24.33Titanium (as TiO2) 0 - 2.8Carbonate (as CO3) 0 - 2.6Silicon (as Si02) 17.3 -63.6Phosphorus (as P202) 0.07-47.2Potassium ( as K20) 2.8 - 3.0Sodium (as Na20) 0.2 - 0.9Undetermined 0.08-18.9
a Ignition loss
b. Particle Size
Estimated particle size distributions " forfour broad classifications of combustionequipment are listed below. All distributionsrepresent the size of the particles leaving theboiler or furnace before any control equip-ment. The distributions reported for all fourequipment classifications ranged widely;those shown 'in the table are considered"typical."
WEIGHT PERCENT LESS THAN STATED SIZE
Pulverized FuelFired Furnace
CycloneFurnace
SpreaderStoker-Fired
Furnace
Stoker-Fired(Other-thanSpreader)
30 76 . 10 750 83 20 1570 90 37 2680 ..92 47 3685 94 54 4390 95 60 5096 97 66
H. SUMMARYAerodispersed solid and liquid particles
constitute a significant fraction of the pollut-ants found in urban atmospheres. Such par-ticulate matter vary greatly in chemical com-position and consist of multirnolecular assem-blies that may, range in complexity from saltcrystals and acid droplets to heterogeneousliquid and solid aggregates and living cells.In this document, a particle is any dispersedmatter, solid or liquid, in which the indi-
vidual aggregates are larger than singlemolecules (about 0.00020; but smaller thanabout 500/. diameter;
Atmospheric particles have size-dependentdynamic, optical,, and electrical properties,and are characterized by such surface activi-ties as sorption, nucleation, and adhesion.Particles, in the size range below 0.1p. dis-play a behavior similar to that- of moleculesand are :characterized by large. random mo-tions caused by collisions with gas molecules.
09, 27
In addition, they frequently collide with eachother and form larger aggregates. Particleslarger than 1p have significant settling veloci-ties; their motions deviate from the motionof the air in which they are borne, and theirrates of coagulation into larger aggregatesare low. The aerodynamic behavior of parti-cles with diameters from 0.1p to 1/A, is transi-tional between these two regimes. Particleslarger than 10p have rapid settling velocitiesand therefore remain in the air for relativelyshort durations. The size range between 0.1pand 10p accounts for the bulk of the particu-late mass in the atmosphere.
Particles below 0.1p obey the same laws oflight scattering as molecules do and their ef-fects on visibility are inconsequential. Parti-cles very much larger than 1/A, obey the sameoptical laws as macroscopic objects, inter-cepting or scattering light roughly in propor-tion to their cross-sectional area. Particlesbetween 0.1p and a few microns obey the verycomplex scattering laws set forth by Mie.This is the particle size range that is most ef-fective in scattering light. (See Chapter 3.)
Particles in the atmosphere can be said tooriginate by two types of mechanism. Smallparticles in the size range below 1p, arise prin-cipally by condensation and combustion,while the larger particles with the exceptionof rain, snow, hail, and sleet, result fromcomminution. Although the chemical compo-sition of particles below 0.1p diameter hasnot been widely studied, the increase overnatural levels of particles in this size rangeseems to be entirely due to combustion. Com-bustion products and photochemical aerosolsmakeup a large fraction of the particles inthe range of 0.1-1.& to 1-p, diameter. Particlesbetween 1/A, and 10µ generally include localsoil, fine dusts emitted by industry and, atmaritime locations, airborne sea salt. Indus-trial sources of particulate matter includemunicipal incineration, cement plants, steelmills, sulfuric acid manufacturing, industrialfurnaces, kraft pulp mills, and others. Parti-cles larger than 101..i, diameter frequently re-sult from mechanical processes such as high,way construction, wind erosion, grinding,spraying, etc., and include material that isdropped on the ground and pulverized by ve-hicles and pedestrians.
28 40
Dustfa ll measurements provide a roughindex of those particles which readily settleout of the air. Typical values encountered inurban areas range from 0.35 mg/cm2-monthto 3.5 mg/cm2-month (10 tons/mi2-month to100 tons/mi2-month) while values approach-ing 70 mg/cm2-month (2000 tons/mi2-month)have been measured close to very severesources. Levels of dustfall have apparentlydeclined in cities, and dustfall measurementis probably not useful as an index of overallparticulate levels. Nevertheless, dustfall it-self constitutes a nuisance, and its measure-ment provides some indication o1 urbandirtiness.
A number of methods are available tomeasure the mass concentration of suspendedparticles. Optical techniques, such as the sunphotometer, the integrating nephelometer,and light-scattering counters, provide an in-dication of particle concentrations in the sizerange from 0.1p to 10p. Two of the most com-mon instruments for measuring mass con-centrations are spot samplers and high-vol-ume samplers. In the former, air is drawnthrough an exposed portion of a paper tape;then the tape is moved to expose anotherspot. The spots that result on the tape areevaluated optically by measuring their lightreflectance or transmittance. Although thespot sampler is cheap, simple, and rugged, itsuse is better suited to the determination ofrelative rather than absolute mass concen-trations. High-volume samplers employ ablower which "sends air through a specialfilter over a specified time period. By weigh-ing the material collected by the filter, themass concentration can be readily deter-mined; chemical analyses also can be carriedout. High-volume sampling is the method ofchoice for measuring particulate levels. Aswith any other point-sampling method, thelocation of the sampling instrument is verycritical, and data for an entire city should notbe based on a single sample located at asingle place.
Most of the data on suspended particulatescome from the National Air Surveillance Net-work (NASN), which employs the high-vol-tune sampler. NASN currently consists ofabout 200 urban and 30 nonurban stations,and it is supplemented by State and local
networks. Based on these data, annual geo-metric mean concentrations of suspendedparticulate matter range from 60 pg/m3 toabout 200 pg/m3 in urban areas. The maxi-mum average concentrations for 24-hourperiods is about 3 times the annual meanwith values of 7 times the mean occurring inabout 2 percent of the communities. In gen-eral, mean particulate concentrations corre-late with urban population class, but there isa wide range of concentrations within eachurban population class, and many smallercommunities have higher concentrations thanlarger ones. In nonurban areas, typical geo-metric mean concentrations range between10 pg/m3 and 60 pg/m3.
I. REFERENCES1. Kreichelt, T. E., Kemnitz, D. A., and Cuffe, S. T.
"Atmospheric Emissions from the Manufactureof Portland Cement." U.S. Dept. of Health, Edu-cation, and Welfare, National Center for AirPollution Control, Cincinnati, Ohio. PHS-Pub-999-AP-17, 1967.
2. Corn, M. "Nonviable Particles in the Air." In:Air Pollution, Chapt. 3, Vol. 1, 2nd edition, A. C.Stern (ed.), Academic Press, New York. 1968,pp. 47-94.
3. Goetz, A. "Parameters for Biocolloidal Matter inthe Atmosphere." Proc. Atmos. Biol. Conf., 1965,pp. 79-97;
4. "Deposition and Retention Models for InternalDosimetry of the Human Respiratory Tract."Task Group on Lung Dynamics for Committee IIof the International Radiological Protection Com-mission, Chairman, P. E. Morrow. Health Phys-ics, Vol. 12, pp. 173-207, 1966.
5. Cadle, R. D. "Particle Size." Reinhold, Nev't York,1965, 390 pp.
6. Drinker, P. and Hatch, T F. "Industrial Dust,Hygenic Significance, Measurement and Control."2nd edition, McGraw-Hill, 1954, 401 pp.
7. Mie. G. "Beitrage zur Optik triiber Modien,Speziell Kolloidaler Metallosurigen." Ann. Physik,Vol. 25, pp. 377-455, 1908.
8. Robbins, R. C. and Cadle, R. D. "Kinetics of theReaction Between Gaseous Ammonia and Sul-furic Acid Droplets in an Aerosol." J. Phys.Chem., Vol. 62, pp. 469-471, 1958.
9. Goetz, A. and Pueschel, R. "Basic Mechanisms ofPhotochemical Aerosol Formation." Atmos. En-viron., Vol. 1, pp. 287-306, 1967.
10. Smith, B. M., Wagman, J., and Fish, B. R. "In-teraction of Airborne' Particles with Gases." Pre-print. (Presented at the Symposium on Colloidand Surface Chemistry in Air and Watex Pollu-tion, 156th National Meeting, American Chemi-cal Socfety, 'Atlantic City, New Jersey, Septem-ber 11, 1968.) (Also to be submitted for publiCa-
tion in Environmental Science and Technology.)11. Preining, 0., Sheesley, D., and Djordjevic, N.
"The Size Distribution of Aerosols Produced byAir Blast Nebulization." J. Colloid Interface Sci.,Vol. 23, pp. 458-561, 1967.
12. Day, J. A. "Small Droplets from Rupturing Air-Bubble Films." J. Rech. Atmospheriques, Vol. 1,pp. 191-196, 1963.
13. "New York-New Jersey Air Pollution Abate-ment Activity, Phase IIParticulate Matter."U.S. Dept. of Health, Education, and Welfare,National Center for Air Pollution Control, Cin-cinnati, Ohio, December 1967.
14. "Washington, D.C. Metropolitan Area Air Pol-lution Abatement Activity." U.S. Dept. of Health,Education, and Welfare, National Center for AirPollution Control, Cincinnati, Ohio, 1967.
15. Venezia, R. and Ozolins, G. "Air Pollutant Emis-sion Inventory. Interstate Air Pollution Study,Phase II Project Report." U.S. Dept. of Health,Education, and Welfare, National Center for AirPollution Control, Cincinnati, Ohio, 1966.
16. Lemke, E. E., Shaffer, N. R., and Verssen, J. A."Summary of Air Pollution Data for Los AngelesCounty." Air Pollution Control District, LosAngeles, California, 1965.
17. Junge, C. E. "Air Chemistry and. Radioactivity."Academic Press, New York, 1963.
18. "Air Quality Data, 1964-1965." U.S. Dept. ofHealth, Education, and Welfare, Div. of AirPollution, Cincinnati, Ohio, 1966, pp. 1-2.
19. "Air Pollution Measurement of the National AirSampling Network, 1957-1961." U.S. Dept. ofHealth, Education, and Welfare, Div. of Air Pol -.
lution, Cincinnati, Ohio, 1962, pp. 6-8.20. Blifford, I. H. and Meeker, G. 0. "A Factor An-
alysis Model of Large Scale. Pollution." Atmos.Environ., Vol. 1, pp. 147-157, 1967.
21. "National Air Surveillance Networks, Air Qua'.ity Data, 1967." U.S. Dept. of Health, Education,and Welfare, National, Center for Air PollutionControl, Cincinnati, Ohio (in preparation).
22. "The November-December 1962 Air PollutionEpisode in the Eastern United States." U.S.Dept. of Health, Education, and Welfare, Div. ofAir Pollution, Cincinnati, Ohio, PHS-Pub-999-AP-7, 1964.
23. "Thanksgiving 1966 Air Pollution Episode in theEastern United States." U.S. Dept. of Health,Education, and Welfare, \National Air PollutionControl Administration, Durham, North Caro-lina, PHS-Pub-AP-45, 1968
24. McMullen, T. B., Fensterstock, J. C., Faoro, R.B., and Smith, R. "Air Quality and Character.istic Community Parameters." J. Air PollutionControl Assoc., Vol. 18, pp. 545-549, 1968.
25. "Standard Method for Collection and Analysis ofDustfall." In: 1966 Book of ASTM Standards,Part 23, Industrial Water; Atmospheric An-alysis, American Society for Testing .and Mate-rials, Philadelphia, Pennsylvania, pp*. 785-788.Report ASTM Dl 739-62.
C.
26. Nadel, J. A. "Dust Retention Efficiencies of Dust-fall Collectors." J. Air Pollution Control Assoc.,Vol. 8, pp. 35-38, 1958.
27. Sanderson, H. P., Brandt, P., and Katz, M. "AStudy of Dustfall on the Basis of ReplicatedLatin Square Arrangements of Various Typesof Collectors." J. Air Pollution Control Assoc.,Vol. 13, pp. 461-466, 1963.
28. Sensenbaugh, J. D. and Hemeon, W. C. L. "Vari-ables in Monthly Dustfall Measurements." Am.Soc. Testing Mater. Proc., Vol. 53, pp. 1160-1165,1953.
29. Gruber, C. W. and Jutze, G. A. "The Use ofSticky Paper in an Air Pollution Monitoring Pro-gram." J. Air Pollution Control Assoc., Vol. 7,pp. 116-117, 1957.
30. Diem, M. and Jurksch, G. "Vergleichsmessungendes Staubgehalts der Luft nach Niederschlags-und Konzentrationsmethoden." Staub, Vol. 21,pp. 245-355, 1961.
31. Shelden, J. M. and Hewson, E. W. "AtmosphericPollution by Aeroallergens." Progress Report No.3, 1 May 1958 to 30 June 1959, University ofMichigan Research Institute, Ann Arbor, Michi-gan, June 1959, pp. 66-70.
32. Hamilton, R. J. and Walton, W. H. "The Selec-tive Sampling of Respirable Dust." In: InhaledParticles and Vapours, 1st edition, C. N. Davies(ed.), Pergamon Press, London, England, 1961,pp. 465-481.
33. Slater, R. W. "Low Cost Measurement of AirPollution." Bull. Univ. Missouri, Vol. 64, pp. 49-53, 1963. (See also Slater, R. W., same title, Ind.Water Wastes, Vol. 8, pp. 30-33, 1963.)
34. Stoeber, W. "Zur Bestimmung von Teilchengros-senverteilungen mit einem Horizontal-Elutria-tor." Staub, Vol. 24; pp. 221-223, 1964.
35. Robson, C. D. and Foster, K. E. "Evaluation ofAir Particulate Sampling Equipment." Am. Ind.Hyg. Assoc. J., Vol. 23, pp. 404-410, 1962.
36. Lippmann, M. and Harris, W. B. "Size-SelectiveSamplers for Estimating 'Respirable' Dust Con-centrations." Health Physics, Vol. 8, pp. 155-163,1962.
37. Roesler, J. R. "Applications of PolyurethaneFoam Filter for Respirable Dust Separation." J.Air Pollution. Control Assoc., Vol. 16, pp. 30-34,1966.
88. Andersen, A. A. "A Sampler for RespiratoryHealth. Hazard Assessment" Am. Ind. Hyg.Assoc. J., Vol. 27, pp. 160-165, 1966.
39. Dessens, J. "Un capteur classeur de particules alame unique." Bull. Obs. Puy de Dome, 1-13,1961. .
40. McCrone, W. C., Draftz, R. G., Ronald, G., andDeily, J. G. "The Particle Atlas." Science Pub-lishers, Inc., Ann Arbor, Michigan, 1967, 406 pp.
41. Lodge, J. P. "Identification of Aerosols." In:Advances in Geophysics, Vol. 9, H. E. Lands-berg and J. Van Miegham (eds.), AcademicPress, New York, 1962, pp. 97-130.
42. Lodge, J. P. and Pate, J. B. "Air Analysis and
804 1,
Atmospheric Pollution." In: Treatise on Analyti-cal Chemistry, Part III, Vol. 2, Sect. D, I. M.Kolthoff and P. J. Elving (eds.), Interscience,New York. (In press, 1968).
43. West, P. W. "Chemical Analysis of InorganicParticulate Pollutant." In: Air Pollution, Chap-ter 19, Vol. 2, 2nd edition, A. C. Stern (ed.),Academic Press, New York, 1968, pp. 147-185.
44. Hoffman, P. and Wynder, E. L. "Chemical An-alysis and Carcinogenic Bioassay of OrganicParticulate Pollutants." In: Air Pollution, Chapt.20, Vol. 2, 2nd edition, A. C. Stern (ed.), Aca-demic Press, New York, 1968, pp. 187-247.
45. Volz, F. "Photometer mit Selen-Photoelement zurspektralen Messung der Sonnenstrahlung andzur Bestimmung der Wellenlfingenabhangigkeitder Dunsttriibung." Arch. Meteorol., Geophys..,Bioklimatol., Ser. B, Vol. 10, pp. 100-131, 1959.
46. Fischer, W. H. and Swartztrauber, P. Unpub-lished manuscript, 1968.
47. McCormick, R. A. and Baulch, D. M. "The Varia-tion with Height of the Dust Loading over aCity as Determined from the Atmospheric Tur-bidity." J. Air Pollution Control Assoc., Vol. 12,pp. 492-496, 1962..
48. Charlson, R. J., Horvath, H., and Pueschel, R. F."The Direct Measurement of Atmospheric LightScattering Coefficient for Studies of Visibilityand Air Pollution." Atmos. Environ., Vol. 1, pp.469-478, 1967.
49. Gucker, F. T., O'Konski, C. T., Pickard, H. B.,and Pitts, J. N., Jr. "A Photoelectric Counter forColloidal Particles." J. Am. Chem. Soc., Vol. 69,pp. 2422-2431, 1947.
50. Roesler, J. R., Stevenson, H. J. R., and Nader,J. S. "Size Distribution of Sulfate Aerosols inthe Ambient Air." J. Air Pollution ControlAssoc., Vol. 15, pp. 576-679, 1965.
51. Corn, M. and DeMaio, L. "Particulate Sulfates inPittsburgh Air." J. Air Pollution Control Assoc.,Vol. 15, pp. 26-30, 1965.
52. Wagman, J., Lee, R. E., Jr., and Axt, C. J. "In-fluence of Some Atmospheric Variables on theConcentration and Particle Size Distribution ofSulfate in Urban Air." Atmos. Environ., Vol. 1,pp. 479 -489, 1967.
53. Lee, R. E., Jr., Patterson, R. K., and Wagman,J. "Particle Size Distribution of Metal Com-ponents in Urban Air." Environ. Sci. Technol.,Vol. 2, pp. 288-290, 1968.
54. Robinson, E. and Ludwig, F. L. "Size Distribu-tions of Atmospheric Lead Aerosols." StanfordResearch Institute, Menlo Park, California, FinalReport SRI. Project PA-4788, 1964.
55. Ludwig, F. L. and Robinson, E. "Size Distribu-tion of Sulfur-Containing Compounds in Urban,Aerosols." J. Colloid Sci., Vol. 20, pp. 571-584,1965.
56. Ludwig, F. L and Robinson, E. "Variations inthe Size Distributions of Sulfur-Containing Com-pounds -in Urban Aerosols." Atmos. Environ.,Vol. 2, pp. 13-23, 1968.
57. Goetz, A. "A New Impaction Device for the De-termination of Aerosol Levels and Particle Con-stitution." Preprint. (Presented at the 152ndAnnual Meeting, American Chemical Society,New York, September 11-16, 1966.)
58. Spumy, K. and Lodge, J. P. "Die Aerosolfiltra-tion mit Hilfe der Kernporenfilter." Staub, Vol.28, pp. 179-186, 1968.
59. Frank, E. R. and Lodge, J. P. "MorphologicalIdentification of Airborne Particles with theElectron Microscope." J. Microscopie, Vol. 4, pp.449-456, 1967.
60. Hemeon, W. C. L., Haines, G. F., Jr., and Ide,H. M. "Determination of Haze and Smoke Con-centration by Filter Paper Samplers." Air Re-pair, Vol. 3, pp. 22-28, 1953.
61. Stalker, W. W., Dickerson, R. C., and Kramer,G. D. "Atmospheric Sulfur Dioxide and Particu-late Matter, a Comparison of Methods of Meas-urement." Am. Ind. Hyg. Assoc. J., Vol. 24, pp.68-79, 1963.
62. Park, J. C., Keagy, D. M., and Stalker, W. W."Developments in the Use of the A. I. S. I. Auto-matic Smoke Sampler." J. Air Pollution ControlAssoc., Vol. 10, pp. 303-306, 1960.
63. "Methods of Measuring Air Pollution. Report ofthe Working Party on Methods of MeasuringAir Pollution and Survey Techniques." Organi-zation for Economic Cooperation and Develop-ment, Paris, France, 1964, 94 pp.
64. Kemeny, E. "The Determination of GravimetricPollution Concentrations by Means of FilterPaper." J. Air Pollution Control Assoc., Vol. 12, .
pp. 278-281, 1962.65. Ellison, J. M. "Die Schlitzung der Konzentration
teilchenformiger Luftverunreinigungen durchBestimmung des Verschmutzungsgrades von Fil-tertapieren." Staub, Vol. 28, pp. 240-246, 1968.
66. Sullivan, J. L. "The Calibration of Smoke Den-sity." J. Air Pollution Control Assoc., Vol. 12,pp. 474-478, 1962.
67. Clark, J. G. "Calibration of Dr. Owen's Appara-tus, for the Estimation of Suspended Solid Pollu-tion in the Atmosphere. Report on Observationsin the Year 1966-67." Advisory Committee onAir Pollution.
68. Sanderson, H. P. and Katz, M. "The OpticalEvaluation of Smokes or Particulate Matter Col-lected on Filter Paper." J. Air Pollution Con-trol Assoc., Vol. 13, pp. 476-482, 1963.
69. Rich, T. A., Pollak, L. W., and Metnieks, A. L."Estimation of Average Size of Submicron Par-ticles from the Number of All and UnchargedParticles." Geofis. Pura Appl., Vol. 44, pp. 233-241, 1959..
70. Megaw, W. J. "Recent Research on Small Ionsand Aitken. Nuclei." J. Rech. Atmospheriques,
Vol. 2, pp.. 53-68, 1966.71. Orr, C., Hurd, F. K., Hendrix, W. P., and Junge,
C. E. "The Behavior of Condensation Nucleiunder Changing Humidities." J. Meteorol., Vol.15, pp. 240-242, 1958.
72. Whitby, K. T. and Clark, W. E. "Electric Aero-sol Particle Connecting and Size DistributionMeasuring System for the 0.015 to 1it SizeRange." Tellus, Vol. 18, pp. 573-586, 1966.
73. Tufts, B. J. and Lodge, J. P. "Chemical Identifi-cation of Halide and Sulfate in Submicron Par-ticles." Anal. Chem., Vol. 30, pp. 300-303, 1958.
74. Strauss, W. "Cleaning Waste Gases from OpenHearth Steel Processes." Chem. Process Eng.,Vol. 41, pp. 339-343, 331, 1960.
75. Purvance, W. T. "Atmospheric Pollution Con-trol." Chem. Process Eng., Vol. 55, pp. 49-53,1959.
76. Silverman, L. "Technical Aspects of High Tem-perature Gas Cleaning for Steel Making Proc-esses." Air Repair, Vol. 4, pp. 189-196, 321, 1955.
77. Chass, R. L. and Rose, A. H. "Discharge fromMunicipal Incinerators." Preprint. (Presentedat the 46th Annual Meeting, Air Pollution Con-trol Association, 1953.)
78. Jens, W. and Rehm, F. R. "Municipal k...ziner-ation and Air Pollution Control." Preprint.(Presented at the National Incinerator Con-ference, American Society of Mechanical Engi-neers, New York, May 20-24, 1966.)
79. Kaiser, E. R. "Refuse Composition and Flue GasAnalyses from Municipal Incinerators." Proc.Natl. Incinerator Conf., American Society of Me-chanical Engineers, 1964. pp. 35-51.
80. "Atmospheric Emissions from Sulfuric AcidManufacturing Processes. A Cooperative StudyProject of the Manufacturing Chemists' Associa-tion, Inc." U.S. -Dept. of Health, Education, andWelfare, Div. of Air Pollution, Cincinnati, Ohio,PHS-Pub-999-AP-13, 1965.
81. Doherty, R. E. "Current Status and Future Pros-pects, Cement Mill Air Pollution Control." Proc.Natl. Conf. Air Pollution, Washington,' D.C.,1966, pp. 242-249.
82. "Motor Vehicles, Air Pollution, and Health. Areport of the Surgeon General to the U.S. Con-gress." U.S. Dept. of Health, Education, andWelfare, National Center for Air Pollution Con-trol, Washington, D.C. 1962.
83. Mueller, P. K., Helwig, H. L., Alcocer, A. E.,Gong, W. K., and Jones E. E. "Concentration ofFine Particles and Lead in Car Exhaust." Amer-ican Society for Testing and Materials, Spec.Tech. Pub. 352,1964, pp. 60-73.Lee, R. E., Jr., Patterson, R. K., Crider, W. L.,and Wagman, J. "Concentration and ParticleSize Distribution of Particulate Emissions inAuto Exhaust." 1968. (Manuscript in Prepara-tion).
85. Bowden, A. T., Draper, P., and Rowling, H. "TheProblem of Fuel Oil Deposition in Open CycleGas Turbines." Am. Inst. Mech. Engrs. Proc.,Vol. 167, pp. 291-300, 1953.
86. MacPhee, R. D., Taylor, J. R. and Chaney, A. L."Some Data on Particles from Fuel Oil Burn-
.,
84.
ing." Air Pollution Control District, Air AnalysisDivision, Los Angeles, California, Analysis Paper7, November 18, 1957.
87. Smith, W. S. "Atmospheric Emissions from FuelOil Combustion." U.S. Dept of Health, Educa-tion, and Welfare, Div. of Air Pollution, Cincin-
nati, Ohio, PHS-Pub-999-AP-2, November 1962.88. Smith, W. S. and, Gruber, C. W. "Atmospheric
Emissions from Coal Combustion. An InventoryGuide." U.S. Dept of Health, Education, andWelfare, Div. of Air Pollution, Cincinnati, Ohio,PHS-Pub-999-AP-24, April 1966.
Chapter 2
EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ONSOLAR RADIATION AND CLIMATE
NEAR THE GROUND
Table of ContentsPage
A. INTRODUCTION 35
B. EFFECTS OF PARTICULATE MATTER IN THE ATMOSPHEREON VISIBLEMADIATION 35
C. EFFECTS OF PARTICULATE MATTER IN THE ATMOSPHEREON TOTAL SOLAR RADIATION 381. Physical Factors 382. Seasonal Variations 393. Weekly Variations 394. Other Variations 40
D. INFLUENCE ON PRECIPITATION 40
E. RELATION TO WORLDWIDE CLIMATE CHANGE 42
F. SUMMARY 43
G. REFERENCES 44
List of FiguresFigure2-1 Relation of Solar Transmissivity to Height Above Ground in "Pol-
luted" and "Clean" Areas 362-2 Annual Variation of the Ratio of Illumination Levels in Central Lon-
don and at Kew (*), and of Concentration of Particulate matter atkew (o) 37
2-3 Causes of Cyclical Diurnal Smoke Variations 412-4 Yearly Cycle (Averaged Over Six Years) of Deposited Pollutants 412-5 Precipitation Values at Selected Indiana Stations and Smoke-Haze
Days at Chicago 42
List of TablesTable2-1 Approximate Association Between Atmospheric Aerosol Concentra-
tions and Relative Solar Radiation Levels2-2 Loss of Sun's Radiation in Three European Cities Over That in the
Adjacent Country2-3 Mean Number of Condensation Nuclei for Various Ranges of Dust
Concentrations in City Air
84
39
40
40
Chapter 2 .
EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON ,SOLAR RADIATIONAND CLIMATE NEAR THE GROUND
A. INTRODUCTION
Particles in the atmosphere play severalroles in the behavior and determination ofthe weather. Among the most obvious is theeffect they have on the radiation from thesun: They scatter the light to greater or lesserextents in different wavelength regions, de-pending on their size, character, and concen-tration, and thus provide- the sky with itsvariable hues, its colorful dawns and sunsets,and also dense hazes and dark urban palls.More subtle changes are occasioned by parti-cles when they reduce the amount of solar en-ergy that reaches the ground.
Particles play a less advertised but veryessential role in the formation of clouds.Without them, liquid water clouds could notform except at supersaturations of severalhundred percent. However, the sort of parti-cles required (called condensation nuclei) areprovided in overabundance by natural proc-esses. Only to the extent that higher-than-normal nuclei concentrations can affect thecloud-forming process, does man's introduc-tion of additional particulate material intothe atmosphere produce changes in observedcloud structure and occurrence.
The kinds of particles which cause precipi-tation from clouds, in contrast to those neces-sary for cloud formation, are frequently inshort supply in the atmosphere. In warm(above freezing) clouds, the requirement isa wide distribution of condensation nuclei,some .of which are giant hygroscopic nucleilarger than 1/L. These "giants" promote therapid growth of cloud droplets by producingsome droplets large enough to fall with re-spect to the others. These grow rapidly bysweeping up smaller drops and very soon be-
come massive enough to fall from the base ofthe cloud as rain.
Another kind of particle is required tostimulate the rapid transformation of clouddroplets into precipitation in supercooled(subfreezing) parts of clouds. Such particlesare termed freezing nuclei. Without these,the water droplets would not freeze exceptat temperatures below 40°C. Once frozen,small ice particles grow rapidly at the ex-pense of the surrounding water droplets andbegin to fall as snow. They may later melt tobecome rain. Dramatic changes in cloudstructure have been achieved by seeding su-persaturated clouds with appropriate freez-ing nuclei. There is evidence, discussed below,that some observed changes in precipitationpatterns in a few sections of the country canbe ascribed to the inadvertent seeding ofclouds by industrial contaminants.
Finally, tentative as our current informa-tion and understanding may be, the long-range potential effect of adding more andmore particles to the atmosphere cannot beignored. As more is learned about the generalcirculation of the atmosphere and the deli-cate balance betireen incoming and outgoingradiation (the "throttle on the atmosphericengine"), it seems increasingly possible thatsmall changes such as those occasioned by in-creasing particle loads in the atmospheremay produce very long-term meteorologicaleffects.
B. EFFECTS OF PARTICULATE MATTERIN THE ATMOSPHERE ON VISIBLE
RADIATION
Stable particles of negligible fall velocityare probably the most common and persistentair pollutants. Their optical effects in produc-
35
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W30
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Y
67
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-1. R
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M.
ing haziness, atmospheric turbidity, and areduction of visibility which hampers thesafe operation of aircraft and motor vehicles,are well known. (See Chapter 3.) The solarradiation transmissivity /1o[A] whereIN is the intensity of the normal-incidencesolar radiation and Io [A] is the extra-terres-trial value at this wavelength) varies withheight and is strongly influenced by the dustloading in the lower atmosphere.' Figure 2-1illustrates the relation. of transmissivity atA =5000 A to height in the atmosphere abovean urban area under varying conditions ofparticulate loading. In the case of heavilypolluted air, thii radiation may be reduced bymore than one-half in the lowest 300 metersof the atmosphere. There is also an increasedattenuation of visible radiation near theground in clean air but, the amount is smallby comparison (Figure 2-1).
It is well known that the reduction or at-tenuation of visible radiation in industrial-ized urban areas, and the attendant gloomcaused by excessive concentrations of sus-pended particles in the air, create a needfor additional artificial illumination in of-fices, factories, and homes, and producesadded economic stresses. This is particularlytrue in winter, when the days are shorterand the particulate content of the urbanair is greater because of greater combustionof fuels. Data given by *Shepherd I illustratesome relationship, shown in Figure 2-2, be-tween particle concentrations and relativevisible radiation levels in London duringsummer and winter months. Daylight illumi-nation was measured at two sites, one in cen-tral London, the other in Kew Observatory, aslightly less heavily polluted area 13 milesWSW of the first site. As another example,the average loss of sunlight in the city ofLeningrad compared to the countryside wasestimated to be 40 percent over the period ofa 'year; in winter the loss was estimated toreach 70 percent in the city, while in summerthe loss was about 10 percent.'
Haze in the atmosphere due to forest fires,dust storms, or smoke from other sources,may become so concentrated at times thatthe sun appears red in the sky despite theabsence of clouds. Just after sunrise or justbefore sunset, the haze may reduce the in-
JAN.
FEB.
MAR.
APR.
MAY
JUNE
JULY
AUG.
SEPT.
OCT.
NOV.
DOC.
JAN.
VISIBLE RADIATIONLONDON/KEW
I4UI b
PARTICULATE LOADINGAT KEW, mg/m3
FIGURE 2-2. Annual Variation of the Ratio of Visi-ble Radiation Levels in Central London and atKew (), and of Concentration of ParticulateMatter at Kew (o) ' (This figure indicates therelative attenuation of light at two sites in a largecity.)
tensity of the direct sunlight so much thatone can look directly at the sun without eyestrain or injury. In other words, haze inthe atmosphere due to suspended particlesscatters the light from the sun, making itappear dim.
Scattering of the sunlight by the particlesmakes the air seem "turbid," and an opticaldevice called the Volz sun photometer has`been devised to measure this "turbidity"quantitatively .4 Starting with equations 3-2in Chapter 3 (Lambert's Law), one calcu-lates from the readings of this instrumenta "turbidity coefficient," B, related to theextinction coefficient b in equation 3-2, Chap-ter 3, or more specifically to b..t definedthere. The relationship between B and bis outlined by McCormick and Baulch, whofound that in a city B, the value of B meas-ured by the Volz instrument at a height ofz meters above the ground, is related to B0,the .value of B measured near ground level,by the equation
B.= BA-0.00346z
37
(2-1).
From scattering theory, McCormick andBaulch estimate that at any height, z, up to200 meters above the ground, the number ofparticles per cubic meter, n' (z) , in the ra-dius range between 0.714 and 114 is given by
n' (z ) =17.3 x 10°B.e-0.003460 (2_2)
Both of these equations are rough approxi-mations for light-wind, clear-sky conditionsin a city during moderate to heavy pollu-tion situations. In terms of mass loadingnear the ground, [m' (o)],
rre(o)103130 (itgm-3) (2-3)
C. EFFECTS OF PARTICULATE MATTERIN THE ATMOSPHERE ON TOTAL
SOLAR RADIATION
Landsberg 5 reports that cities in generalreceive 15 percent to 20 percent less insola-tion (on a horizontal surface) than do theirrural environs. Insolation, as used here,means the total solar radiation received atthe earth's surface per unit area per unittime. This discussion considers the part thatairborne particles take in the diminution ofinsolation received by cities.
1. Physical Factors
The attenuation of solar radiation throughthe atmosphere is caused by a number ofphysical factors: 2.0-10
1. Scattering of radiation, known asRayleigh scattering, by the air mole-cules, such as N2 and 0,, and par-ticles in size ranges less than thewavelength of the solar radiation(the scattering coefficient is inverselyIroportional to the fourth power ofthe wavelength of the incident ra-diation; hence the short wavelengthradiation is scattered most, so thatthe sky appears to be blue)
2. Selective absorption by the gaseousconstituents of the atmosphere suchas ozone and C0, and by water va-por; and
3. Scattering and absorption by atmos-pheric dusts and particulate matterof size greater than in (a).
The attenuation of solar radiation by wa-
88
ter vapor and ozone is negligible in the visiblewavelength region usually studied.6. 7' 11
The scattering of light by aerosol particlesin ambient air is a complicated process. Fartof the incident light is transmitted, part isreflected in all directions either at the frontsurface of the particle or at an internal dis-continuity, and part is absorbed. The trans-mission factor for scattering is a functionof the wavelength of the incident light andthe physical qualities of the scattering me-dium. In simple cases where the form, size,and composition of !the scattering particlesare known, the factor can be derived on atheoretical basis and is known as "Mie" scat-tering. Chapter 3 provides a more extendeddiscussion. .
Diffuse radiation is an important factorin the amount of heat and light received atany given location.3.1° The intensity andspectral distribution of direct sunlight andscattered daylight, and the varation of in-tensity with time of diy, season, latitude,altitude, and atmospheric conditions such asturbidity, are important because they affectphotosynthesis in plants and the distribu-tion of plants and animals on earth, theweathering of natural and man-made ma-terials, climate, and illumination for humanactivity.° The percentage of direct solar ra-diation which will remain after its attenua-tion by smoke and other atmospheric con-tituents depends both on the atmospheric
tu bidity caused by the smoke, and on thealtitudeof the sun above the horizon, as wellas on the Other Jactorsi° previously noted.
Except in casetof heavy particulate pollu-tion of the atmospheie, . such as may occurin large urban centers Or heavy industryareas, it appears that the effect of turbidityis to scatter radiation out of the direct solarbeam and to add an almost equal amount ofradiation to the diffuse beam arriving fromthe rest of the sky by forward-scattering.In cases of heavy particle concentrations,however, the loss from the direct solar beamgreatly exceeds the gain in the downwardscattered beam, the difference being hist, toback-scattering off the top of the pollutionlayer and to absorption within the pollutedlayer or column.
Studies indicate a fair approximation of
the association between atmospheric aerosolconcentration and relative solar radiationlevels, as shown in Table 2-1.
Table 2-1.APPROXIMATE ASSOCIATION BE.TWEEN ATMOSPHERIC AEROSOL CONCEN-TRATIONS AND RELATIVE SOLAR RADIA-TION LEVELS.
Solar radiation, percent ofAerosol concentration, value for 100p18 m-3
pg m-3 Total Ultraviolet
50 105 104100 100 100200 95 92400 90 '7'7
The reduction in ultraviolet light reachingthe surface may be as important as the at-tenuation of other, longer wave, componentsof solar radiation. Available data are sparsebut one study 12 indicates that ultraviolet in-tensity decreased by about 7.5 percent foreach 100 pg/m-3 increase in aerosol content of the atmosphere with an average de-ficiency of over 20 percent in the city as com-pared with its environs in winter. Somestudies suggest that a 5 percent reductionin total solar radiation resulting from smokealmost completely eliminates the ultravioletcomponent.3.12 Even in a comparativelyclean atmosphere, the effective' ultravioletdrops to very low values when the sun's ele-vation is below 30 degrees.''
The net influence of atmospheric turbidityon surface temperature is uncertain, but fortypical turbidity indices in the United States,it is likely to be small. The effect on solarradiation (warming in the upper region ofthe pollution layer due to extinction by theupper region) tends to be compensated bythe effect on radiation returning to spacefrom the earth's surface and atmosphere.The extent to which the solar radiation effectprevails over the terrestrial radiation effect,or vice versa, is dependent on a number offactors which include: .
1. the time of day and year (on whichthe intensity of solar radiation is it-self dependent) ;
2. the total mass and vertical distribu-tion of the particles;
3. the size distribution of the particles;4. relative humidity, which, in the case
of hygroscopic aerosols, may alterthe effective absorptivity and reflec-tivity of the particles; and
5. temperature of the air and ground(on which the intensity of the terres-trial radiation depends).
2. Seasonal Variations
The concentration of suspended particu-late matter which ranges from less than 60pg/m3 to 1700 pg/m3 in various Americancities shows a notable annual variation.Autumn and winter particulate levels are in-variably highest, and summer levels lowest.The weakening of radiation caused by smokeis less during the summer when the sun ishigh than in the winter. This would betrue even if there were the same degree ofpollution in the air. The losses in intensityof direct total solar radiation during its pas-sage through an atmosphere polluted bysmoke may become as high as one-third inthe summer and two-thirds in the winter.'
Landsberg has summarized the radiationloss data compiled by Steinhauser 13 for threeCentral European citiesFrankfurt, Leip-zig, Viennaand their adjacent rural areas;for the four seasons of the year. There arecontrasts in loss of solar radiation betweenspring or summer and Winter, as will beseen in Tabr2-2. Steinhauser and co-workers 13 also reported that Vienna, receivesa lesser total radiation than the nearby coun-tryside: in winter 85 percent of the totalsolar radiation of suburban Hoche Warte,in spring 92 percent, in summer 92 percent,and in autumn 87 percent. ". 13 The' absorp-tion is strongest in the short (ultraviolet)wavelengths.", ". 13' 14
This annual cycle is observed to be a func-tion of latitude, dependent on the changingmidday sun angle. The scattered radiationduring the summer months (May-August)may amount to approximately 60 percent to65 percent of the direct radiation at 60° lati-tude and to about 45 percent at 40° latitude.
3. Weekly VariationsIn addition to the seasonal and diurnal
variations or patterns of total solar radia-
51 39
A
tion in urban communities, a weekly cycleof intensity of total solar radiation has beenobserved,22-22 which is related to the weeklycycle of industrial and commercial activity.In general, the total solar radiation receivedis inversely related to the concentration ofsmoke and suspended particles; thus solarradiation measurements may be used, in theabsence of clouds, as a crude index of par-ticulate air pollution.
Table 2-2.LOSS OF SUN'S RADIATION INTHREE EUROPEAN CITIES OVER THAT INTHE ADJACENT COUNTRY.'
Solar Elevation
Season 10° 20° 30° 45° .
Percent Percent Percent PercentWinter 36 26 21Spring 29 20 15 11Summer 29 21 18 14Autumn 34 23 19. 16
r
Mat:eer " studied the total solar and skyradiation patterns in metropolitan Torontofrom October 1937 to 1960 and compared theradiation received on Sundays to the aver-age of the weekday radiation readings atthe same central site. The average radiationon Sundays for this period was 313.8 lang-leys (1 langley= 1 g cal/cm2) while the meanfor the weekday radiation was 305.2 lang-leys, a difference of 8.6 langleys or 2.8 per-cent. The probability of obtaining such adifference by chance was less than 0.5 per-cent. Thus, while a real difference in radia-tion exists between Sundays and weekdays,the magnitude is rather small.
4. Other VariationsHand 18 has noted that the average daily
solar, radiation in various cities was signifi-cantly higher over the entire year 1932 thanover the prior year. The largest increase insolar radiation was found to be in New YorkCity ( +21.9 percent), while Pittsburgh andWashington showed yearly increases of 6.2percent and 8 percent respectively. The busi-ness depression was probably a major factorin this increase. Records for New York,Chicago, and Pittsburgh for the year 1932
40
showed the marked diminution in dust andsmoke levels resulting from the falling offin the amount of manufacturing during thisperiod.
D. INFLUENCE ON PRECIPITATION
There is evidence that some of the parti-cles introduced into the atmosphere by man'sactivities can act as nuclei in processes whichaffect the formation of clouds and precipi-tation.
Condensation nuclei in the size rangegreater than 11& are often made up of hygro-scopic particles. 2° Because of their affinityfor water, these particles play an importantrole in the transformation and condensationof water vapor into liquid water droplets orsolid ice particles, and are of vital impor-tance in the formation of fog, clouds, andrain. Combustion products of man's indus-try and technology, as well as volcanic erup-tions and ocean sprayf are significant sourcesof these nuclei. A parallelism exists betweenthe concentration of dust and that of conden-sation nuclei in city air. (See Table 2-3.)
Table 2-3.MEAN NUMBER OF CONDENSATIONNUCLEI FOR VARIOUS RANGES OF DUSTCONCENTRATIONS IN CITY AIR."'
Number ofdust particles
per cm'
Mean number ofcondensation nuclei
per cm'<500 189,000
500-999 211,000>999 223,000
A pronounced parallelism can also befound with respect to diurnal and annualvariations in the contents of atmosphericdust and nuclei." 12-22 The excess productionof condensation nuclei in the air over citiesis a long established fact,'. 20, 23 and has beenreaffirmed with many amplifying circum-stances." 23 Evidence has been presentedthat giant nuclei, which may initiate the coa-lescence process, are more abundant in in-dustrial areas than elsewhere."
The diurnal, weekly, and yearly cycles ofboth suspended and dustfall particle concen-trations, correspond closely to man's patternof activities and combustion requirements.There are usually two diurnal peaks (see
Figure 2-8), greater midweek concentrationscompared to Sundays, and greater mean con-centrations in winter than in summer (seeFigure 2-4)."
A correlation has been found between pat-terns of precipitation over cities and the ad-
a! INIFFItIENTOMBUSTIONFFECT
S
::1 I°4, EFFECT OF
TURBULENCEVe
,,,;;;,,Y% COAL CONSUMPTION'
0 L.o '21 4 6
SMOKE' FROM NEIGHBORINGDISTRICTS
SMOKECONCENTRATION
"4444;I A
8 10 12 14 16 18 20 22 24CLOCK TIME
FIGURE 2-3. Causes of Cyclical Diurnal Smoke Vari-ations.° (This figure shows causes of changes inthe diurnal airborne particulate concentration inan urban location.)
Wci >-
u. a § z z U,1 U Wa to 0 2 0
FIGURE 2-4. Yearly Cycle (Averaged Over SixYears) of Deposited Pollutants. (This figure illus-trates the variation of amount of pollutants de-posited at Leicester town hall averaged over thesix years ending March 1939, and shows thegreater mean concentration in winter as comparedwith summer.)
jacent countryside and the variations of par-ticle concentrations in the atmosphere.22-24The influence of cities on precipitation iscomplex; however, there is a general tend-ency for urban factors to increase precipita-tion." These factors, not necessarily in orderof importance, are:
1. water vapor addition from combus-tion sources and processes;
2. thermal updrafts from local heating;3. updrafts from increased friction tur-
bulence;4. added condensation nuclei leading to
more ready cloud formation; and,5. added nuclei which may act as freez-
ing nuclei for super-cooled cloud par-ticles.
Landsberg 23 cites as evidence the gradualincrease of rainfall which followed thegrowth of Tulsa, Oklahoma, from a villageto a city in five decades and the concomitantincrease in particle concentrations. A studyby Kline and Brier 25 in metropolitan Wash-ington, D.C., indicates that there is a con-siderably higher level of freezing nuclei inthe metropolitan area than there is in the ad-jacent countryside.
Ashworth 24 first suggested the correlationbetween the weekly cycle of smoke in indus-trial areas and that of precipitation. Fred-erick," in a more recent analysis, showed adefinite minimum Sunday rainfall for a ten-year period in Louisville, Pittsburgh, andBuffalo.". 28 Precipitation occurred in theseless often on Sundays than on other daysof the week, and the average rainfall wasless for Sundays than for weekdays. Astrong city influence is also suggested in thesnow patterns in Toronto.27
An interesting and significant increase inprecipitation has been observed at La Porte,Indiana, since 1925. La Porte is 30 mileseast of the large complex of heavy indus-tries in the metropolitan Chicago area.Changnon 28 compared precipitation at LaPorte, Valparaiso, and South Bend, Indiana,with a five-year moving average of the num-ber of smoky and hazy days in Chicago (Fig-ure 2-5). The temporal distribution of thesmoke-haze days after 1980 is rather similarto the La Porte curve. A notable increase in
it41
smoke-haze days began in 1935, becomingmore marked after 1940, coincident with thesharp increase in the La Porte precipitationcurve. The reduction in the frequency ofsmoke-haze days after the peak reached in1947 also generally matches the decline ofthe La Porte curve since 1947.28
Stout " has shown that the shape of thetime - series curve for. La Porte precipitationalso generally matched a time-series curvefor annual steel production in the Chicagoindustrial complex. Between 1905 and 1965,peaks in steel production, which occurredwhen production in most other industrieswas also high, were all associated with highpoints in the La. Porte precipitation curve.
The effect of industrial pollution on pre-cipitation has also been studied by Telford."
300
270
240
210
i so
He found that smoke from steel furnaces wasa prolific source of freezing nuclei, increas-ing counts by a factor of 50 over those innearby clean air. He concluded that thereshould be increased rainfall downwind ofsuch installations.
E. RELATION TO WORLDWIDECLIMATIC CHANGE
Theoretical considerations and empiricalevidence indicate that atmospheric turbidity,itself a function of aerosol concentration, isan important factor in the heat balance ofthe earth-atmosphere system. The observedincrease in turbidity over the past few dec-ades may play a role in the reported decreasein worldwide air temperature since 1940 byincreasing the planetary albedo.7. al
150
OBSERVERCHANGES ATLA PORTE
LA PORTE,
CHICAGOSMOKE HAZEDAYS
SOUTH BEND
. /" .001 1 1
1910 1920 1930 1940 1950 1950
1800
1400
0-,06
I-<Nx0z
02(I)
1 000
LL0600
2
200
0
ENDING YEAR OF 5-YEAR MOVING AVERAGE
FIOURE 2-6. Precipitation Values at Selected Indiana Stations and SmokeHaze Days at Chicago. (This figureshows the way in which precipitation trends at La Porte follow the haze changes in Chicago. The results areplotted as five-year moving averages.)
42
Angstrom estimated roughly that a changein the albedo from 0.40 to 0.41 correspondsto a change in the mean temperature of theearth-atmospheric system of close to 1° C."Humphreys 33 made similar calculations withroughly the same results, and also showedthat the interception of outgoing radiationby fine atmospheric dusts is wholly negligiblein comparison with the interception of in-coming solar radiation. .Temporal and spa-tial changes in the atmospheric turbidity of100 percent, corresponding to albedo changesof 10 percent to 15.percent, from one dayto the next or from one locality to another,are very commonplace." Even though thesefigures may well overestimate the actualchanges brought about in atmospheric tem-peratures, the course of atmospheric turbid-ity over the earth is an important climaticfactor.
There are data available 3'. " from whichthe trend in turbidity during the past cen-tury can be estimated. Angstrom gave 0.098as the value of the mean annual turbidity atWashington, D.C. (1903 to 1907) ," and0.024 as the value at the Davos Observatory,Switzerland (1914' to 1926). The values forWashington Were determined from data onsolar transmission (by wavelength) pub-lished by the Smithsonian Institution; thosefor Davos were from data attributed to Lind-holm on dust absorption. In 1962, deter-minations of the atmospheric turbidity werebegun at the Continuous Air MonitoringProgram station 31' 33 of the. Public HealthService, near the Smithsonian Institution;the mean annual turbidity, recorded for 1962to 1966 was 0.154,33 a 57 percent increaseover the 1.903 to 1907 values. From 1957to 1959, determinations of atmospheric tur-bidity were again made for Davos by Valko 33and were given as 0.043, a 70 percent in-crease.
When the scattering theory with a Jungedistribution of particle size* is used, thevalues of turbidity change imply an increasein the average annual number of aerosol par-ticles, in the range of 0.1.A to 1A radius, of2.8 x 107cm2 and 0.95 X 107/cm2 over Wash-ington and Davos respectively, during theperiods shown. Nearly two-thirds of theWashington increase might be attributed to
the increased population and urbanization ofthe District since the turn of the century.A significant remainder, however, as judgedby the Davos increase, may be indicative ofa much more general buildup of atmosphericaerosol.
When the above facts are put together,they indicate that for Washington, D.C., dur-ing the period 1903 to 1966, there has beena possible decrease of nearly 3 percent inthe total available solar energy at groundlevel and a possible increase in the averageannual number of aerosol particles of2.8 x 107cm2. The net effect of this apparentsecular increase in turbidity (which fromthe Davos, Switzerland, and other evidence"appears likely to be worldwide) is probablyto increase the mean albedo of the planetand reduce the mean temperature of theearth-atmosphere system.
The increase in atmospheric turbidityconsequent upon volcanic eruptions mayhave temporary effects on atmospheric tem-peratures. Mitchell 3" concluded that tem-peratures over large areas of the world maybe depressed by 0.5° F or more in the firstor second year following an unusually violenteruption. However, McCormick and Lud-wig 3' suggest that the effects of man's pol-lution of his environment are increasingsteadily along with the world population.The emission of long-lived particles, keepingpace with the accelerated worldwide produc-tion of CO.,, may well be leading to the de-crease in world air temperature in spite ofthe apparent buildup of CO:.'"
F. SUMMARY
Atmospheric particles scatter and absorblight from the sun, thus reducing the visibleradiation available to cities and the solarradiation that reaches the earth. The gloomdue to reduced illumination in urban areascreates a need for artificial lighting in offices,factories, and homes and produces relatedeconomic stresses. The average year-roundillumination (i.e., the portion of the spec-trum that is visible to the eye) may be re-duced by one-third or more in some cities.Daylight illumination in the center of Lon-don, for example, was found to be 20 per-cent less than that found at a slightly less-
48
polluted part of the city quite near the center.Part of the sunlight reaching the earth
comes from the direct beam and part fromthat scattered from the rest of the sky. Thetotal solar energy reaching the earth is thesum of both the direct and the scattered ra-diation. In general, cities receive 15 per-cent to 20 percent less total solar radiationthan do rural environments, although the netreduction may be considerably greater undersome circumstances. For a typical urbanarea in the United States, with a geometricmean annual concentration of roughly 100pg/m3, the total sunlight is reduced approxi-mately 5 percent for every doubling of par-ticle concentration. This effect is more pro-nounced on the ultraviolet portions of thespectrum.
Diurnal, weekly, and yearly cycles of bothsuspended particulates and dustfall particlescorrespond closely to man's pattern of activi-ties and his combustion requirements. Thereare usually two daily peaks, greater midweekconcentrations compared with Sundays, andgreater mean concentrations in autumn andwinter than in spring and summer. The sea-sonal variations are due largely to the useof coal and heavy fuel oil for heating pur-poses. Solar radiation attenuation patternsalso show weekly and seasonal variations.On weekdays, the attenuation is slightlymore than on Sundays, and the losses in in-tensity of the direct beam during its passagethrough an atmosphere polluted by smokemay become as high as one-third in the sum-mer and two-thirds in the winter. Even vari-ations from year to year have been noted;for example, levels of total solar radiationmeasured in various cities were significantlyhigher in 1932 than in the prior year, un-doubtedly because of the decline in manu-facturing and industrial activity broughtabout by the depression. Reductions in theintensity. of solar radiation or changes in itsspectral distribution have significance forthe photosynthesis of vegetation, the distri-bution of plants and animals on the earth,the weathering of natural and manmade ma-terials, and man's aesthetic enjoyment andphysical well-being.
The increased emission of fine particlesinto the atmosphere also may cause changes
44
in the delicate heat balance of the earth-atmosphere system, thus altering worldwideclimatic conditions. The rise in atmosphericturbidity increases the planetary reflectivity,or albedo, and reduces the solar energy avail-able to maintain surface temperatures. Thisphenomenon may be responsible for the re-ported decrease in worldwide temperaturesince the 1940's. Comparisons at differentsites over the world covering periods as longas fifty years suggest that a general world-wide rise in turbidity may be taking place.This may well be indicative of a gradualbuildup of worldwide background levels ofsuspended particulates. The increasing lev-els of atmospheric carbon dioxide resultingfrom man's combustion of fuels probablyexerts an opposite effect on worldwide tem-peratures, but the emission of long-lived par-ticles to the air may gradually depress worldair temperature despite the. apparent build-up of carbon dioxide.
Some of the particles introduced into theatmosphere by man's activities also can af-fect the weather by serving as condensationnuclei that influence the formation of clouds,rain, and snow. The large airborne particlesgenerated in metropolitan areas serve as abase for the condensation of moisture and
_ lead to the rapid formation of rain dropletsor ice crystals. Patterns of precipitationover cities and the adjacent countryside haveshown a correlation with particle concentra-tions in the atmosphere. Some cities displaya definite minimum rainfall on Sundays,when particulate levels are usually lowest,and records over several decades reveal thatrainfall levels may increase with the con-comitant rise in particulate levels that gen-erally accompanies urban growth. In addi-tion, long-term changes in the frequency ofsmoke-haze days in one city may affect rain-fall levels in a nearby downwind city.
Thus airborne particles can, through anumber of mechanisms, influence man's sur-roundings, and have considerable impact onweather and climatic conditions.
G. REFERENCES
1. Sheppard, P. A. "The Effect of Pollution onRadiation in the Atmosphere." Intern. J. AirPollution, Vol. 1, pp. 81-43, 1958.
It
2. McCormick, R. A. and Baulch, D. M. "The Vari-ation with Height of the Dust Loading over aCity as Determined from the Atmospheric Tur-bidity." J. Air Pollution Control Assoc., Vol. 12,pp. 492-496, 1962.
3. Sheleikhovskii, G. V. "Smoke Pollution ofTowns." Akademiya Kammunal'nogo Khzyaistvaim. K. D. Pamfilova. [Academy of MunicipalEconomy im. K. D. Pamfilova.] Izdatel'stvo Min-
isterstva Kommunal'nogo Khozyaistva RSFSR,Moskva-Leningrad. 1949. (Translated fromRussian and published for the National ScienceFoundation, Washington,.D.C. by the Israel Pro-gram for Scientific translations, Jerusalem,1961.)
4. Volz, F. "Photometer mit Selen-Photoelementzur spektralen Messung der Sonnenstrahlungund zur Bestimmung der Wellenlangenabhangig-keit der Dunsttrubung." Arch. Meterol. Geophys.Bioklimatol., Ser. B, Vol. 10, pp 100-131, 1959.
5. Landsberg, H. "Physical Climatology." 2nd edi-tion, Gray, DuBois, Pennsylvania, 1958, pp. 317 -326.
6. Angstrom, A. K. "On the Atmospheric Trans-mission of Sun Radiation II." Geograph. Ann.(Stockholm), Vol. 12, pp. 139-159, 1930.
7. McCormick, . R. A. "Atmospheric Turbidity."Preprint. (Presented at the 60th Annual Meet-ing, Air Pollution Control Association, Cleve-land, Ohio, June 11-16, 1967.)
8. Stagg, J. M. "Solar Radiation of Kew Observa-tory." Air Ministry, Meteorological Office, Lon-don, Geophysical Memoirs 86, 1950.
9. Gates, D. M. "Spectral Distribution of SolarRadiation at the Earth's Surface." Science, Vol.151, pp. 523-529, 1966.
10. Robinson, N. "Solar Radiation." Elsevier, Am-sterdam, London and New York, 1966.
11. Angstrom, A. K. "On the Atmospheric Trans-mission of Sun Radiation and Dust in the Air."Geograph. Ann. (Stockholm), Vol. 11, pp. 156-166, 1929.
12. Shrader, J. H., Coblentz, M. H., and Korff, F. A."Effect of Atmospheric Pollution upon Incidenceof Solar Ultraviolet Light." Am. J. PublicHealth, Vol. 19, pp. 717-724, 1929.
13. Steinhauser, F., Eckel, 0., and Sauberer, F."Klima und Bioklima von Wien." Wetter undLeben, Vol. 7, 1955, 120 pp.
14. Kenrick, G. W. and Ortiz, H. "Measurementsof Ultra-Violet Solar Radiation in Puerto Rico."Trans. Am. Geophy. Union, 19th, 1938, pp. 138-140.
15. Meetham, 'A. R. "Atmospheric Pollution inLeicester. A Scientific Survey." Dept. of Scien-tific and Industrial Research, London, Atmos-pheric Pollution Research Technical Paper 1,1945.
16. Meetham, A. R. "Atmospheric Pollution: ItsOrigin and Prevention." Pergamon Press, NewYork, 1961. 4
(
17. Mateer, C. L. "Note on the Effect of the WeeklyCycle of Air Pollution on Solar Radiation atToronto." Intern. J. Air Water Pollution, Vol.4, pp. 52-54, 1961.
18. Hand, I. F. "Solar Radiation MeasurementsDuring December 1932." Monthly Weather Rev.,Vol. 60, pp. 256-257, 1932.
19. Neuberger, II. "Condensation Nuclei: Their Sig-nificance in Atmospheric Pollution." Mech. Eng.,Vol. 70, pp. 221-225, 1948.
20. Landsberg, H. "Atmospheric Condensation Nu-clei." Erg. Kosm. Physik., Vol. 3, pp. 155-252,1938.
21. Giner, R. and Hess, V. F. "Studie uber die Ver-teilung der Aerosole in der Luft von Innsbrukund Umgebung." Gerlands Beitr. Geophys., Vol.50, pp. 22-43, 1937.
XT. Georgii, H. W. "Probleme und Stand der Erfor-schung des Atmospharischen Aerosols." Ber.Deutsche Wetterdienste., Vol. 7, pp. 44-52, 1959.
23. Landsberg, H. "City AirBetter or Worse."In: Air Over Cities Symposium, U.S. Dept. ofHealth, Education, and Welfare, Robert A. TaftSanitary Engineering Center, Cincinnati, Ohio,Technical Report A62-5, 1962, pp. 1-22.
24. Ashworth, J. R. "The Inil.ence of Smoke andHot Gases from Factory Chimneys on Rainfall."Quart. J. Roy. Meteorol. Soc., Vol. 55, pp. 341-350, 1929.
25. Kline, D. B. and Brier, G. W. "Some Experi-ences on the Measurement of Natural Ice Nu-clei." Monthly Weather Rev., Vol. 89, pp. 263-272, 1961.
26. Frederick, R. H. Personal communication. U.S.Weather Bureau.
27. Potter, J. G. "Chan.ges in Seasonal Snowfall inCities." Canadian Geographer, Vol. 5, pp. 37-42,1961.
28. Changnon, S. A. Jr. "The La Porte WeatherAnomaly, Fact or Fiction." Bull. Am. Meteorol.Soc., Vol. 49, pp. 4-11, 1968.
29. Stout, G. E. "Some Observations of Cloud Ini-tiation in Industrial Areas." In: Air Over CitiesSymposium, U.S. Dept. of Health, Education,and Welfare, Robert A. Taft Sanitary Engineer-ing Center, Cincinnati, Ohio, Technical ReportA62-5, 1962, pp. 147-153.
30. Telford, J. W. "Freezing Nuclei from IndustrialProcesses." J. Meteorol., Vol. 17, pp. 676-679,1960.
31. McCormick, R. A. and Ludwig, J. H. "ClimateModification by Atmospheric Aerosols." Science,Vol. 156, pp. 1358-1359, 1967.
32. Angstrom, A. K. "Atmospheric Turbidity, Glo-bal Illuminators and Planetary Albedo of theEarth." Tellus, Vol. 14, pp. 435-450, 1962.
33. Humphreys, W. J. "Volcanic Dust and OtherFactors in the Production of Climatic Changesand their Possible Relation to Ice Ages." Bull.Mount. Weather Observatory, Vol. 6, pp. 1-34,1914.
57 45
It
34. Peterson, J. T. and Bryson, R. A. "AtmosphericAerosols: Increased Concentrations During theLast Decade." Science, Vol. 162, pp. 120-121,1968.
35. "Atmospheric Turbidity Report." U.S. Dept. ofHealth, Education, and Welfare, National Cen-ter for Air Pollution Control, Cincinnati, Ohio.(Quarterly)
36. Valko, P. "Untersuchung Uber die vertikaleTriibungsschichtung der AtmosphUre." Arch.
46
Meteorol. Geophys. Bioldimatol., Ser. B, Vol. 11,pp. 143-210, 1961.
37. Mitchell, J. M., Jr. "Recent Secular Changes inGlobal Temperatures." Ann. N.Y. Acad. Sci.,Vol. 95, pp. 235-250,1961.
38. "Restoring the Quality of Our Environment."Report of the Environmental Pollution Panel,President's Science Advisory Committee, TheWhite House, Washington, D.C., November 1965,pp. 111-131.
.5S
Chapter 3
EFFECTS OF ATMOSPHERIC PARTICULATEMATTER ON VISIBILITY
u -
Table of ContentsPogo
A. INTRODUCTION 51
B. IMPORTANCE OF ATMOSPHERIC AEROSOLS TO THE GEN-ERAL OPTICAL PROBLEM 51
C. PHYSICAL RELATIONSHIPS BETWEEN VISIBILITY AND PAR-TICLE CONCENTRATION 52
D. COMPLICATIONS AND LIMITATIONS IN THE VISIBILITYPROBLEM 531. Smoke Plumes 532. Natural Aerosols and Hazes 533. Fogs 54
E. THE LOW-HUMIDITY, WELL-AGED HAZE 541. Size Distribution 542. Mie Solutions 543. Dependence of Extinction of Particle Size for the Atmospheric Case,4. The Mass-Light Scattering Relationship 55
F. DETERMINATION OF WELL-DEFINED CASES OF MASS-VISIBILITY RELATIONSHIPS 58
G. METHODS FOR DETERMINING LIGHT SCATTERING COEFI-CIENT-MASS CONCENTRATION RELATIONSHIP 59
H. SUMMARY 60
I. REFERENCES 61
List of FiguresFigure3-1 Four TypiCal Measured Size Distributions of Atmospheric Suspended
Particles Together with the Corresponding Visibilities 543-2 The Relation of Scattering Cross-Section to Particle Size for Parti-
cles of Three Different Refractive Indices 553-3 Cross Section Curve for Typical Atmospheric Size Distribution , . .... 553-4 The Dependence of Scattering Coefficient (nr!) on Volume of Aero-
sol Particles (1.0/cm3) Calculated from Measured Size Distributions 563-5 Measured Dependence of Mass of Aerosol Particles per Volume (4/
m3) on the Light Scattering Coefficient (mr-I) in Seattle, November-December 196i3 56
3-6 Histogram of Equivalent Visual Range-Mass Concentration Productat Several Locations 57
3-7 Relation Between Visual Range and the Mass Concentration 573-8 Three Horizontal Profiles through the City of Seattle Taken under
Differing Meteorological Conditions 59
48
60
List of TablesTable3-1 Relation Between Equivalent Visual Range and
tion
3-2 The Relative Humidity at which Phase Changeliquescent Aerosols
tws
Particle Concentra-
Occurs in Some De-
Page
57
59
,fs
Chapter 3
EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON VISIBILITY
A. INTRODUCTIONOne of the dramatic effects of air pollu-
tion is a degradation of the visibility. Visi-bility in the atmosphere is reduced by twooptical effects which air molecules and aero-sol particles have upon visible radiation. Oneis the attenuation by the molecules and par-ticles of the light, passing from object to ob-server. It is the result both of absorptionof light and of the scattering of light out ofthe incident beam. The light received fromthe object and that received from its back-ground are diminished by this attenuation,and the difference between the two (con-trast) is consequently diminished with theresult that the eye's ability to distinguish theobject from its background is reduced. Theother optical effect that degrades the contrastbetween object and background is the illumi-nation of the intervening air which resultswhen sunlight is scattered into the line ofsight by the molecules and particles in theline of sight. It is a common observationthat dark objects become progressivelylighter in shade as they become more distant.The most distant mountain that one can dis-tinguish typically is almost as light or brightas its sky background.
In those cases where a clear-cut relation-ship can be shown to exist between visibilityand the mass of suspended particles per vol-ume of air (mass concentration), it is pos-sible to use some of the meteorological visi-bility records t) infer the amount of pollu-tion in past years as well as to study trends.In fact, many such studies have been madeeven without a substantive knowledge of therelationship. Holzworth 1 used existing visi-bility data both as an indication of theamount of pollution for comparison of anurban (Columbus, Ohio) area with a ruralarea, and for the qualitative inference of
trends of both increasing and decreasingamounts of smoke or other atmospheric aero-sol. Robinson 2 also discussed the use of me-teorological visibility records and theirinterpretation. Both Holzworth 1 and Robin-son = demonstrated that visibility degrada-tion can be associated with air pollution.Neither, however, developed the sort of cor-relation between mass of suspended particu-late matter per volume of air and visibilitythat is needed for air quality criteria. Rob-inson indicated doubt in the existence of agenerally applicable relationship betweenmass concentration and visibility. Thisdoubt was based on experimental results aswell as on the complexity of the problem.Recent experimental and theoretical ad-vances make possible some useful conchi-sions, and this chapter will define a simplerelationship between .mass of suspended par-tic/e9 and visibility, specify the circum-stances under which it can be expected to bereliable, and describe the conditions whichare too complex for this simple treatment.
In the United States, the words visibilityand visual range are usually used synony-mously to mean the distance at which it isjust possible to perceive an object againstthe horizon sky. Middleton 3 reports thatthe originator of both terms intended thatonly visual range be considered as a distance,while visibility should convey a more quali-tative judgment about the clearness of see-ing. In this chapter, however, the terms visi-bility and visual range will be used inter-changeably to mean a distance.
B. IMPORTANCE OF ATMOSPHERICAEROSOLS TO THE GENERAL
OPTICAL PROBLEMDecreased visibility obviously interferes
with certain important human activities,
51
62'
such as the safe operation of aircraft andautomobiles and the enjoyment of scenicvistas. The effect of decreased visibility onthe large-scale operations of commercial air-craft in metropolitan areas is a problem ofgrowing concern. The Federal Air Regula-tions of 19674 (paragraphs 91.105 and91.107) prescribe limitations on aircraft op-eration that become increasingly severe asvisibility decreases below five miles. Most re-strictions are invoked when the visibility isbelow three miles. In areas with a high den-sity of aircraft traffic, visibilities much belowfive miles tend to slow down operations bymaintaining larger separations between air-craft. Even though most commercial air-planes always fly under Instrument FlightRules rather than Visual Flight Rules, good
. visibility increases both the safety and per-mitted traffic density. Light airplane opera-tions are limited even more severely whenvisibility is less than three miles, because oftheir limited 'instrument flight capability.
A 1963 report by the Civil AeronauticsBoard to the Committee on Public Works,U.S. Senate,r states that records of both au-tomobile and aircraft accidents show caseswhere poor visibility due to smoke and airpollution was an important causal factor.Evidence presented at Federal air pollutionabatement conferences 6' shows the exist-ence of air pollution that curtails visibility,endangering the safety of people travelingby both land and air, and in addition, causinginconvenience and economic loss to the pub-lic and to transportation companies due todisruption of traffic schedules.
C. PHYSICAL RELATIONSHIPSBETWEEN VISIBILITY ANDPARTICLE CONCENTRATION
Many deriyations of visibility theory havebeen published. Although Robinson's 2 ap-proach is directed towards the air pollutionproblem, Middleton's 3 book presents a morecomplete view of the problem of atmosphericclarity.
For the simplest case of attenuation of alight beam along its path, the intensity, I,decreases by an increment dI over the in-
52
crement of path dx. The relationship be-tween intensity and distance is:
dI= b dxI
or, in integrated form,
I= Ioe-bx
(3-1)
(3-2)
where b is the extinction coefficient assumedto be constant over x, and I. represents theintensity of light at x = 0.
The extinction coefficient, b, is the sum offour terms:
1. the scattering coefficient of the air mole-cules, b
Rayleigh "2. the scattering coefficient of particles or
aerosol, bscat
3. the light absorption by gases, babs -gas'
and,4. the light absorption by the aerosol, b
abs-aerosol.
Of these four, the scattering due to aerosolis usually assumed to dominate in haze.= Theprocess of scattering amounts to the removalof light from the original beam and its redis-tribution in different directions. Scatteringthus differs from absorption in which thelight energy is lost to the absorber; in scatter-ing, the light energy is only spatially redis-tributed. Nonetheless, this removal of lightfrom the beam (or line of viewing) does re-sult in extinction. It suffices to state only thefinal result in equation 3-2 for the usualassumption of 2% contrast threshold for an"average" human eye.2.8
L = 3.9v b
scat (3-3)
Here, L, is the visual range in meters andb is, as before, the extinction coefficient permeter along the path of sight for the case ofa black object. If b is determined at a pointwithout knowledge of the entire sight path,then L, is "equivalent visual range," i.e., thedistance one could see if the extinction coeffi-cient were constant along the sight path. Adiscussion of the dependence of extinctioncoefficient on the amount of atmosphericaerosol follows in Section F.
"Visual quality" as perceived by even thewell-trained observer is not so easily describ-ed. Among the complications is the fact thatparticles responsible for urban haze scattermore light in a direction close to that of theoriginal beam (so-called forward-scatter)and less light in a backward direction. Thus,the same haze may appear to be much moredense when looking toward the sun and lessdense when looking away from the sun.
Besides this directional factor, there is alsoa wavelength (or color) dependence. Ang-strom,9 Junge,9 and others have shown thatthe extinction coefficient of hazes in generalis inversely proportional to a power of wave-length:
b = 1Aa (3-4)
where a has measured values of around 1.0 to1.5. This relation indicates that blue light (ofshorter wavelengths) will be scattered to agreater degree than red light (of longerwavelengths). It is for this reason that thdsun's disc, when observed through a haze thatis dense enough to permit such viewing, ap-pears red, orange or even brown though lightabsorption is not necessarily occurring.
D. COMPLICATIONS AND LIMITATIONSIN THE VISIBILITY PROBLEM
1. Smoke PlumesConner and Hodkinson," in tests on the
optical properties of well-controlled experi-mental smoke, found that visual effects arenot inherent properties of the plumes butvary with the background of the plume andwith illuminating and viewing conditions.Variation was much greater with whiteplumes than with black. Tests conducted withtrained smoke inspectors showed that theirevaluations of non-black smoke plumes were 2. Natural Aerosols and Hazessignificantly influenced by these variations. The general problem of natural particu-
At least two real difficulties exist in making --late matterfrom whatever sourcemustany generalizations about visual aspects ofsmoke plumes. First, it is not possible to de-termine the mass emitted per unit time froma smokestack solely, on the basis of visuallyperceived light scatter or absorption. Themass per unit time emitted from the stackand not the appearance or optical properties
of the plume is pertinent to the eventual aircomposition, even though appearance may beaesthetically objectionable.
Secondly, although many meteorologicalmixing equations have been proposed, theycannot describe individual eddies of smoke asthe plume disintegratesmThe equations weremeant for describing averages and not aninstantaneous property such as the extinctionof light in some particular eddy of smoke asdetermined by eye, perhaps with the aid of aRingelmann Chart.
Because of these probleMs, the topics ofplumes and plume optics are discussed onlybriefly in this chapter, and the presentationis concerned primarily with the aerosol pro-duced after the initial meteorological mixingof the plume has occurred. The reader is re-ferred for further information on plume op-tics to the study by Conner and Hodkinson."
The Ringelmann number may provide anobjective measurement of public sentimentregarding the disagreeable appearance ofsmoke plumes, although aesthetic aspects aredifficult to quantify.-Robinson 2 shows the as-sumptions and size distribution informationthat are necessary for relating plume opacityto the aerosol content of smoke.
The difficulties inherent in visual evalua-tion of smoke plumes do not eliminate thepossibility of using such observations as anaid in controlling air pollution. In principle,the Ringelmann Chart should be useful inestimating the obscuring of vision by plumesand in setting limits to control the visibilitydegradation downwind from a source of particulate matter. In practice, however, theproblem is extremely complex and requiresextensive study to develop better techniquesfor measuring the contribution of individualplumes to visibility problems.
be considered. The oceans produce salt parti-cles, tiees produce terpenes that may resultin organic particles," forest fires makesmoke, and so on. Man has little hope of con-trolling the quality of air that enters theurban areas from uninhabited lands. None-theless, these low-humidity aerosols some-
s4 63
times cause dramatic reduction in the visualrange. In order to properly evaluate the im-portance of natural aerosols, the visibilityof the air mass should be determined beforeit enters a populated area.
3. Fogs
When the relative humidity exceeds 'ap-proximately 70 percent, many types of parti-cles exhibit deliquescent behavior and growinto fog droplets. Natural particles such assodium chloride from the sea as well as manyproducts of human activity can thus act ascondensation nuclei (Chapter 2). The prop-erty of deliquescence and the relative humid-ity at which rapid and large change in parti-cle size occurs are both very dependent onthe chemical composition and original sizeof the particles. As a result, unless the chem-ical composition as a function of particle sizeis known for the aerosol, very little can besaid about the relationship between visibil-ity in even "thin" fog and the amount ofmaterial present as pollutant."
Because little deliquescence occurs below70 percent relative humidity, the relation-ships to be presented here will be limited tothe range of humidity from 0 percent to 70percent. In cases of higher humidity, it ispossible to decrease the relative humidity ofthe air by heating it for optical evaluationof the amount of particulate matter, as de-scribed by Charlson et al." This humiditylimitation has already been adopted in Cal-ifornia."
E. THE LOW-HUMIDITY, WELL-AGEDHAZE
1. Size Distribution
Recent advances in both theory and .tech-nology have resulted in a simplification ofthe description of well-aged aerosols. Junge,9Friedlander," Whitby," and others 17 haveshown that aerosols in the lowest region ofthe atmosphere (troposphere) , whether overurban areas or not, tend to have similar sizedistributions. Figure 3-1 shows several typi-cal size distributions to illustrate this fea-ture.
If it is assumed that this recurring sizedistribution exists in general, then it is pos-
54
Z.
<). 1
Nz
z
0: 104Wo.8
103
c.)
< 102o.LL0CC
sot" 1012z
34 m i l e s has low w i n d weed-high pressure over area. Seattle
45 miles hue deep low pressurewee southwest of erns Sunk
67 mileemin showeis and cumulusclouds tops now moo foe.Suttee
1040 miles (omen) high pressureover wee. Washington seacoast
.01I rIitt11_ I I I I 'is LI
0.1 1.0
PARTICLE RADIUS.p
FIGURE 3-1. Four Typical Measured Size Distribu-tions of Atmospheric Suspended Particles To-gether with the Corresponding Visibilities." (Thefigure shows that aerosols in the lowest region ofthe atmosphere (the troposphere) tend always tohave similar size distributions.)
sible to relate the optical properties of thehaze to the amount or mass concentration ofmaterial present. This generalization maynot apply to freshly-formed smoke. Briefguidelines for determining when the sizedistribution has become sufficiently well-defined will be .given later.
2. The SolutionsAs mentioned earlier, another important
assumption which is usually made is that, ofthe four extinction components, light scatter-ing by aerosols dominates. Current researchindicates that this is probably a justifiableassumption." Figure 3-2 shows typical scat-tering cross sections for green light as afunction of particle size for aerosol particlesimportant in haze, computed via the theoryof Gustav Mie." For some particle sizes, dif-ferences in the scattering coefficient of a fac-tor of three exist between the two refractiveindices which 'span the realistic range forthe atmospheric case. However, Pueschel and
aq
Q1PARTICLE RADIUS, #
FIGURE 3-2. The Relation of Scattering Cross-Sec-tion to Particle Size for Particles of Three Dif-ferent Refractive Indices." (The figure shows thatthe scattering cross-section of atmospheric par-ticks varies roughly as the cube of their radiuswithin the range 0.1i to 1.0g. The range of re-fractive indices, 1.33 to 1.6, for which the propor-tionality holds includes most materials found inatmospheric aerosols.)
No1119 conclude that the extinction coefficientof aerosols in the troposphere is nearly inde-pendent of the refractive index of the parti-cles if the size distribution is close to thosedescribed in Figure 3-1.
3. Dependence of. Extinction on ParticleSize for the Atmospheric Case
If the data in Figures 3-1 and 3-2 arebroken down into narrow radius intervals(eg., 0.04) , and a calculation performed toyield the extinction coefficient for each ra-dius interval, the particle size dependence ofatmospheric extinction of green light is re-vealed. Figure 3-3 shows the results for atypical size distribution of spherical parti-cles having a refractive index of 1Z.
In general, this procedure shows that anarrow range of particle sizes, usually from0.1p to 1p radius controls the extinction coef-ficient and therefore the visibility: If thevalues of the extinction coefficient for eachradius interval are thin- mmuned, the total.
0r
.0
cc
z
0cc
-110.7
ccOLL
i-z
LLLL
0tt
Ozrc
t-8,o
00 0.1 0.2 0.3 0.4 0.5 0.6 0.7
PARTICLE RADIUS,(p)
FIGURE 3-3. Cross Section Curve for a Typical At-mospheric Size Distribution." (The figure showsthe particle size dependence of atmospheric ex-tinction obtained by breaking down the data ofFigures 3-1 and 3-2 into 0.01p,-radius intervals,to yield the extinction coefficient of each radiusinterval.)
extinction coefficient, due to scatter, b.t, isobtained.
1. The Mass-Light Scattering RelationshipIt is also possible to calculate the volume
of particulate matter per unit volume of air(i.e., in cubic microns of aerosol per cubiccentimeter of air). The familiar quantity ofareosol mass concentration (a/m9) is pro-portional to this volume ratio via the particledensity. Figure 3-4 shows the calculated rela-tionship of aerosol volume (10/cm9) to scat-tering coefficient per meter. (for green light[5500A] and for a refractive index of 1.6)based on 82 individual measured size distri-butions. Sixteen of . these size distributionsused in Figure 3-4 were measured in Seattleunder varying meteorological conditions. The,remaining 16 were obtained in the AustrianAlps under conditions where, presumably,
55
SEATTLE, WASHINGTON .* f/A
%
000 KALKALPEN, AUSTRIA
00
I 11121211 I 21121211 I atoms,
1000
E 300
Z.100
0> 3008ice 10
3
1.00.1 0.3 1.0 3 10 30 x10'4
LIGHT SCATTERING COEFFICIENT bsctim
FIGURE 3-4. The Dependence of Scattering Coeffi-cient (m-') on Volume of Aerosol Particles(iNcne) Calculated from Measured Size Distri-butions." (The solid circles are based on Seattle,Washington, data and the open circles on Kalkal-pen, Austria, data.)
only natural aerosol was present. The im-plication of these calculations is that thevolume, and thus the mass concentration ofwell-aged aerosol, is approximately propor-tional to the light scattering coefficient foratmospheric aerosols originating naturallyor as the result of man's activity."
It follows, therefore, that even though theaerosol mass is distributed over perhaps twoor three decades of size, and light scatter iscaused by particles of one narrow size range,a proportionality can exist between the num-ber of particles scattering light and the totalmass concentration of particles. Constantshape of the size distribution here impliesthat for all radius intervals, the number ofparticles in an interval is proportional to thenumber in. the corresponding interval in areference size distribution.
Figure 3-5 shows data obtained by an in-tegrating nephelometer 13 for a wavelengthof 5000. A confirming this calculated depend-ence. The relationship can be summarized asfollows: .
mass (aims) ze 3 X 102 beat /m. (3-5)
Figure 3-6 shows data like those of Figure
56
1000
300
0)100
0I=cc4C 30I
Z 100c.)
030
cc
4C
1.00.1 0.3 1.0 3 10 30
M8
I 1121121 a I 2111w1 2 1 mitattx10-4
LIGHT SCATTERING COEFFICIENT bscatim
FIGURE 3-5. Measured Dependence of Mass of Aero-sol Particles per Volume (pg/m) on the LightScattering Coefficient (m-1) in Seattle, November-December 1966."
3-5 plotted in a different fashion to illustratetheir distribution." From equations 3-3 and3-5, the product of equivalent visual rangeand mass concentration (L, x cone) can beobtained.Since
3.9L,=bscat
multiplying both sides of theconcentration gives
3.9 X coneL, X cone
bacat
The units on both sides of this equation aremass per area (e.g., pg/m2). If we use theparticular proportionality in equation 3-5,then:L. X conc=4.2 x 101 tig/m2= 1.2 g/m2. (3-6)This product has a simple physical signifi-cance: it is the mass of material in a columnof length L, and one square meter in crosssection. In other words, it is the amount ofmaterial per square meter between the ob-server and a point at the limit of visibility.Each point of Figure 3-5 can be used.to formthis number since each pair of values of massconcentration and scattering' coefficient can
(3-3)
uation by
(3-3a)
35,
30.
25.
20
15
10
cc 10.tuco2 5,
0
A. All 238 cases.
rr
B. New York City, 62 cases.
C. San Jose, California,48 cases.
rtwa10.1
5.
0
10
D. Seattle, WashingtonArea. 45 cases
00 4 0.8 1.6k 2.4 3.2
Ly x MASS, grams / m2
E. Seattle, Washington, highvolume air sampler date,83 cases.
FIGURE 3-6. Histogram of Equivalent Visual Range-Mass Concentration Product at Several Loca-tions? (The figure shows the number of caseswith a given range of values of the product ofmass and equivalent visual range for data at vari-ous locations studied. This product represent's' themass required to determine the visibility in a col-ume one square meter in cross section along thelight path.)
be used to obtain a different proportionalityof the sort shown in equation 3-5. Figure 3-6consists of histograms showing the numberof occurrences for different values of thequantity 1,, x cone found at various locations.Here, since the modal value is about 1.2g/m2, one can write:
X (g/m2)to include virtually all cases.
(3-7)
100
E35
*v,
0
11 0MASS CONCENTRATION, icis / m3
FIGURE 3-7. Relation Between Visual Range andMass Concentration." (This figure shows the in-verse proportionality between visual range and
-mass concentration described by equations 3-7 and3-8.)
Equation 3-5 can also be rewritten to includethese upper and lower limits:
mass (tig/m2)= (3:::°) x102 b.t/m (3-8)
Data in essential agreement with this resulthave also been obtained recently by visualmethods in Oakland, California." As thedata indicate that equation 3-8 is applicablein a wide variety of cases," and becausethese locations seem to include a wide varietyof- air pollution character, it is anticipatedthat this generalization may be useful inmany urban areas. The relationship is shownin Figure 3-7 and Table 3-1.22 However, ex-perimental verification of the mass-light ex-tinction relationship is desirable for eachlocation in question.
Table 3-1.-RELATION BETWEEN EQUIVALENTVISUAL RANGE AND PARTICLE CONCENTRA-TION:"
Scattering Equivalent EquivalentMass coefficient visual visual
concentra- due to aerosol, range, range,tion pg/ne bmt/m km miles
1021, 0.3X10" 120.0 75.00
30 1.0X10" 40.0 26.00
100***) 8.3X10" 12.0 7.50
3001°''-NM 10.0X10" 4.0 2.50
1000": 33.0X10" 1.2 0.75
57
r.
The accuracy of equations 3-'1 and 3-8depends on many factors and assumptions.This research area is an active one, and newdata are constantly being acquired. Improve-ments in the understanding of these phe-nomena and the accuracy of descriptions willno doubt occur in the near future. However,these values are known to be accurate to wellwithin one significant figure for the casesmeasured, and their utility for criterion pur-poses is therefore clear.
Photochemical ly produced aerosols, as wellas other organic aerosols, can be expected to
'have similar visibility effects if their sizedistribution remains reasonably constant.Since the physical processes governing sizedistribution are assumed to be largely in-dependent of the chemical nature of the par -ticles," the size distribution should be similarto those shown in Figure 3-1. However, ifsuch particles are volatile or metastable tooxidation as suggested by Goetz," the massdetermination may be difficult. Although vis-ibility degradation is evident in photochem-ical smog, experimentally determined sizedistribution data are needed.
It can be seen from Figure 3-5 that thepractical unit of light scattering coefficientfor 5000 A wavelength is 10-4/m. The value1 x 10-4/m represents fairly clean air with aparticle mass concentration of about 30µg /m', while 10 x 10-4/m represents morepolluted air (concentration about .300 lig/m3). Of course, the reciprocal relationship(equation 3-3) could be used in combinationwith equation 3-5.
L. (km) x 102/conc (iig/m3). (3-9)
(See also Figure 3-7 and Table 3-1.) How-ever, reciprocal relationships are harder tovisualize than are direct proportionalities,and the extinction coefficient due to scatter(or just scattering coefficient) itself canserve as an index for particulate pollution.
It is interesting to compare the results ofequation 3-7 with Robinson's 2 calculation of0.34 g/m2 for an oil aerosol in which all par-ticles have the same 0.6, diameter. Sinee thisestimate represents a case in which all thepirticles are involved in the light scattering,it is not surprising that a mass smaller than
58
that suggested by equation 3-7 is necessaryfor determining the visibility. In the atmos-phere. a large percentage of the mass of theparticulate matter is outside the size classimportant for light scatter (see Figures 3-1and 3-3) and a somewhat higher mass perunit area is needed to determine the visibility.
F. DETERMINATION OF WELL-DEFINEDCASES OF MASS-VISIBILITY
RELATIONSHIPS
. As discussed above, any generalizationabout the visibility-particle (aerosol) con-centration relationship is dependent on awell-defined and nearly constant size distri-bution. The following list summarizes thecases in which equatiori 3-8 applies:
1. the relative humidity should be below70 percent. (For a discussion of therelationship between visibility andconcentrations of sulfur dioxide atvarious relative humidities, see acompanion volume to this document;Air Quality Criteria' for Sulfur Ox-ides.) Absolute humidity is relativelyunimportant since the interaction' ofwater vapor and hygroscopic aero-sols depends mainly on relative hu-midity. In the case of 'a particularlyhygroscopic aerosol, the '70 percentfigure may be unreliable. Table 3-2shows a list of compounds and theapproximate humidity at which theydeliquesce. If such a substance ispresent as a large percentage of thetotal aerosol, even though the restof the following conditions may hold,the applicability of equation 3-5might be open to doubt.
2. the size distribution must be well-established and close to the recurringform discussed earlier. Little experi-mental information is available onthe length of time required for vari-ous types of fumes to attain a reason-ably well-defined size distribution bycoagulation and sedimentation. Meas-urement of this parameter is there-fore desirable before any generaliza-tions are made about visibility. The
6
4
Table 3-2.THE RELATIVE HUMIDITY AT WHICHPHASE CHANGE OCCURS IN SOME DELIQUES-CENT AEROSOLS."
Substance
Approximatepercent relative
humidity atwhich phase
change occursat 25°C
Sodium hydroxide 7Calcium chloride 29Sulfuric acid 35Magnesium chloride 33Sodium iodide 38Magnesium nitrate 53Sodium bromide 58Potassium iodide 69Sodium nitrate 74Sodium chloride 75Potassium bromide 80Potassium chloride 84Barium chloride 90
most important qualification appearsto be that the aerosol in questionmust not be freshly formed as in asmoke plume. Times of the order ofone hour may be adequate for theestablishment of a well-defined sizedistribution from a combustion-pro-duced fume.
3. if visual observations are used, theline of sight cannot pass throughsmoke plumes or freshly formedclouds of fumes. As mentioned ear-lier, the light extinction coefficient isa spatial variable and thus the massinferred by visual methods repre-sents an average over a large dis-tance. If the optical quantity (i.e. ex-tinction coefficient due to scatter) isto be related to concentration meas-urements made at one point in space,then it should be determined at thesame point. To illustrate the possiblemagnitude of the visibility variation,Figure 3-8 shows the variation ofscattering coefficient measured withan integrating nephelometer acrossthe city of Seattle on three days withdifferent meteorological conditions.The results also emphasize the haz-ards inherent in visual observations."
9
E 8
7z
T.U.
O 5
caiv, 3
S 2
.1
020 15 10 5 0 5 10 15 20 25 30
N. SDISTANCE FROM UNIVERSITY HIGH BRIDGE, Km
31 AUGUST 19671000-1030 PDTFOGGYLOW WIND SPEED
II V e,/
/ v/ 30 AUGUST 19671 /
/641530
1615 PDTLOW WIND SPEED
//5 SEPTEMBER 196T1530-1630 PDTSTRONG SOUTH WIND....
........
FIGURE 3-8. Three Horizontal Profiles Through theCity of Seattle Taken Under Differing Meteorolog-ical Conditions.° (The figure illustrates the pos-sible magnitude of variations in visibility.)
G. METHODS FOR DETERMINING LIGHTSCATTERING COEFFICIENT-MASSCONCENTRATION RELATIONSHIP
Methods for determining the extinctioncoefficient and/or the visibility (as relatedthrough equation 3-3) are not as well-es-tablished as for many meteorological quan-tities (e.g. wind, temperature) or for airpollution quantities (dustfall, mass concen-trations, etc.). Three basic approaches canbe differentiated:
1. the method of choice is an instantane-ous point measurement of the ex-tinction coefficient. The extinction co-efficient due to scatter (which is as-sumed to dominate) can be measuredwith an integrating nephelometersuch, as was used by Charlsonet al.". 26. 26
2. the next most desirable methods in-volve the measurement of total ex-tinction coefficient using light trans-
1.70 59
C..
i
mission. Telephotometers of theshortest possible base line might beused, but once again have poor sen-sitivity for typical urban haze. Spe-cially devised instruments have beendesigned and used with great diffi-culty in the range of extinction foundin cities. Typical airport transmis-someters are designed to be useful infog and are thus of little value exceptin cases of extreme pollution and fog.
3. visual methods, though frequentlyused, should be avoided because of.the subjectivity of the eye as a sen-sor and the variations between ob-servers, as well as the spatial varia-tion problem mentioned above. If itIs necessary to use visual observa-tions, the -observers must be methodi-cal and should use the rules adopt-ed by the United States WeatherBureau."
Ordinary methods (i.e. the high-volumeair sampler) for the determination of massconcentration (µg /m') may suffice if care istaken to eliminate spurious large particlessuch as insects, etc. As recent data taken inSeattle show, newer sampling methods usingnewer types of filters are becoming availableand allow a much shorter sampling time.
H. SUMMARY
The visual range, sometimes called the"visibility," is reduced by particulate matterin the air. It refers to the distance at whichit is just possible to perceive and objectagainst the horizon sky. Both the attenua-tion of light from the object and illuminationof the air between the object and the ob-server tend to reduce visibility, since theyreduce the perceived contrast between theobject and its background. Attenuation oflight passing through the air results fromtwo optical effects which air molecules andsmall particles have on visible radiation: (1)the absorption of light energy and (2) thescattering of light out of the incident beam.In general, reduced visibility is primarily aresult of scattering due to particulate mat-ter. The, "extinction coefficient," b,,st, is ameasure of the degree of scattering, and it,060 71
is related to the visual range of a black ob-ject as follows:
3.9L,= (m) (3-3)
bent
Suspended particulates found in the atmos-phere cover a broad range of size; however;the visibility is affected by a relatively nar-row segment of this size distribution, usuallyfrom. about 0.1it to 1it radius. Once particu-late matter has been suspended in the air forsome time, the distribution of particles bysize tends to take on a typical pattern. Be-cause of this, and because the visible lightscattering is caused primarily by particlesof one narrow size range, the scattering canbe empirically related to the particulate con-centration. This relationship is as follows:
A x 103(from 3-9)
G'where G' =particle concentration (µg /m')
L, = equivalent visual rangeA =1.2o a for L. expressed in kilome-
ters and0.7515 for L, expressed in miles.238 .
The ranges that are shown for the constant,A, cover virtually all cases studied. Devia-tions from equation 3-9 would be expected tooccur when the relative humidity exceeds 70percent, since many particles exhibit deli-quescent behavior and grow into fog drop-lets. (For a discussion of the relationship] -
between visibility and sulfur dioxide concen-trations at various relative humidities, seea companion volume to this document, AirQuality Criteria for Sulfur Oxides.) Parti-cles composed of sodium chloride, for ex-ample, would act as condensation nuclei andshow rapid and large changes in size undersuch circumstances. Also, this relationshipmay not hold for photochemical smog, sinceit is not known whether its size distributionconforms to the necessary pattern.
Equation 3-9 provides a convenient meansfor estimating the expected visibility for dif-ferent levels of particulate concentrations,under the conditions stated. With a typicalrural concentration such as 30 µg /m', thevisibility is about 25 miles; for commonurban concentrations, such as 100 µg /m'and 200 itg/ms, the visibility would be 7.5
miles and 3.75 miles, respectively. In addi-tion to aesthetic degradation of the environ-ment, reduced visibility has many conse-quences for the safe operation of aircraftand motor vehicles. When airports haveheavy traffic, visibility below 5 miles tendsto slow operations, since it is necessary tomaintain larger distances between aircraft.Federal air regulations prescribe limitationson aircraft operating under conditions of re-duced visibility; they become increashglysevere as the visibility decreases from 5miles (150 pg/ms) to 3 miles (250 pg/ms)to one mile (750 µg /m9) . Based on the empir-ical variations in equation 3-9, the same vis-ibilities could occur under certain circum-stances, at concentrations one-half of thesecalculated values. Thus; a concentration of75 µg /m9 might produce a visibility of 5miles in some instances.
I. REFERENCES
1. Holzworth, G. C. "Some Effects of Air Pollu-tion on Visibility in and near Cities." In: AirOver Cities Symposium, U.S. Dept. of Health,Education, and Welfare, Robert A. Taft Sani-tary Engineering Center, Cincinnati, Ohio, Tech-nical Report A62-5, 1961, pi. 69-88.
2. Robinson, E. "Effects of Air Pollution on Visi-bility." In: Air Pollution, Chapt. '11, Vol. 1,2nd edition, A. C. Stern (ed.), Academic Press,New York, 1968, pp. 849-400.
3. Middleton, W. E. K. "Vision Through the Atmos-phere." University of Toronto Press, 1952.
4. "Federal Aviation Regulations." Federal Avia-tion Agency, 1967.
5. "A Study of PollutionAir." A staff reportto the Committee on Public Works, U.S. Senate,Washington, D.C., 1967.
6. "New York-New Jersey. Air Pollution AbatementActivity, Phase HParticulate Matter." U.S.Dept. of Health, Education, and Welfare, Na-tional Center for Air Pollution. Control, Wash-ington, D.C., 1967.
7. "Kansas City, Kansas-Kansas City, Missouri,Air Pollution Abatement Activity, Phase IIPre-conference Investigations." U.S. Dept. ofHealth, Education, and Welfare, National Cen-ter for Air Pollution Control, Washington, D.C.,March 1968.
8. Angstrom, A. K. "On the Atmospheric Trans-mission of Sun Radiation II." Geograph. Ann.(Stockholm), Vol. 12, pp. 139-159, 1980.
9. lunge, C. E. 'Air Chemistry and Radioactivity."Academic Press, New York, 1963.
t.
10. Conner, W. D. and Hodkinson, J. R. "OpticalProperties and Visual Effecteof Smoke-StackPlumes." U.S. Dept. of Health, Education, andWelfare, National Center for Air Pollution Con-trol, PHS-Pub-999-AP-30, 1967.
11. Went, F. W. "Dispersion and Disposal of Or-ganic Materials in the Atmosphere." PreprintSeries 31, University of Nevada, Desert Re-search Institute, 1966.
12. Pilat, M. J. and Charlson, R. J. "Theoreticaland Optical Studies of Humidity Effects on theSize Distribution of a Hygroscopic Aerosol." J.Rech. Atmospheriques, Vol. 2, pp. 165-170, 1966.
18. Charlson, R. J., Horvath, H., and Pueschel, R. F."The Direct Measurement of Atmospheric LightScattering Coefficient for Studies of Visibilityand Air Pollution." Atmos. Environ., Vol. 1,pp. 469-478, 1967.
14. "California Standards for Ambient Air Qualityand Motor Vehicle ExhaustTechnical Report."Dept. of Public Health, Berkeley, California,1960.
15. Friedlander, S. K. and Wang, C. S. "The Self-Preserving Particle Size Distribution for Co-agulation by Brownian Motion." J. Colloid In-terface Sci., Vol. 22, pp. 126-132, 1966.
16. Whitby, K. T. and Clark, W. E. "Electric Aero-sol Particle Counting and Size DistributionMeasuring System for the 0.15p to 1p, SizeRange." Tellus, Vol. 18, pp. 573-586, 1966.
17. Peterson, .C. M. and Paulus, H. J. "Microme-teorological Variables Applied to the Analysis!of Variation in Aerosol Concentration and Size."Preprint. (Presented at the 60th Annual Meet-ing, Air Pollution Control Association Cleve-land, Ohio, June 11-16, 1967.)
18. Mie, G. "Beitriige zur Optik triiber Medien,Speziell Kolloidaler Metallosungen." Ann.Physik, Vol. 25, pp. 377 - 455,1968.
19. Pueschel, R. F. and Noll, K. E. "Visibility andAerosol Size Frequency Distribution." J. Appl.Meteorol., Vol. 6, pp. 1045-1052, 1967.
.20. Charlson, R. J., Ahlquist, N. C., and Horvath, H."On the Generality or Correlation of Atmo-spheric Aerosal Mass Concentration and LightScatter." Atmos. Environ., Vol. 2, pp. 455-464,1968.
21. Noll, K. E., Mueller, P. K., and Imada, M. "Visi-bility and Aerosol Concentration in Urban Air."Atmos. Envir- on., Vol. 2, pp. 465-475, 1968.
22. Charlson, R. J. "Atmospheric Aerosol Researchat the University of Washington." J. Air Pol-lution Control Assoc., Vol. 18, pp. 652-654, 1968.
23. Goetz; A., Preining, 0., and Kallai, T. "TheMetastability of Natural and Urban Aerosols."Rev. Geofis. Pura Appl. (Milano), Vol. 60, pp:67-80, 1961.
24. Acheson, D. T. "Vapor Pressures of SathmtedAqueous Salt Solutions." Proc. Intern. Symp.Humidity and Moisture, Washington, D.C., May1968, pp. 521-580.
'472.;
61
25. Ahlquist, N. C. and Char leon, R. J. "Measure-ment of the Vertical and Horizontal Profile ofAerosol Concentration in Urban Air with theIntegrating Nephelometer." Environ. Sci. Tech-nol., Vol. 2, pp. 363- 366,1968.
26. Ahlquist, N. C. and Charlson, R. J. "A New In-strument for Evaluating the Visual Quality of
62:
Air." J. Air Pollution Control Assoc., Vol. 17,pp. 467-469, 1967.
27. "Manual of Surface Observations (WBAN)."Circular N, 7th Edition (Revised to includechanges 1 through 14), U.S. Weather Bureau,January 1968.
.;
Chapter 4
EFFECTS OF ATMOSPHERICPARTICULATE MATTER ON MATERIALS
Table of ContentsPage
A. INTRODUCTION65
B. EFFECTS OF PARTICULATE MATTER ON METALS 65
C. EFFECTS OF PARTICULATE MATTER ON BUILDINGMATERIALS
69
D. SOILING ANDDETERIORATION OF PAINTED SURFACES 71
E. SOILING AND DEGRADATION OF TEXTILES 71
F. SUMMARY72
G. REFERENCES74
List of FiguresFigure
4-1 Plot of Rate of Rusting Versus Dustfall at Four Locations 664-2 Weight Loss from Zinc Specimen as a Function of Exposure Time 674-3 District Building, Washington, D. C :67
zList of Tables
Table
4-1 Corrosion of Open-Hearth Iron Specimens in Different Locations 664-2 Corrosivity of Atmospheres towards Steel and Zinc at Selected Loca-
tions Relative to that at State College 684-3 The Corrosion Rates of Metals in Various Locations 70
Chapter 4
EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON MATERIALS
A. INTRODUCTION
Airborne particles may damage surfacesmerely by settling on them. A light deposit ofdust makes surfaces appear dingy, and thefrequent cleaning necessary in a dusty atmos-phere weakens materials and costs money.
Particles can also cause direct or chemicaldeterioration of materials. The nature andextent of the deterioration depends on thechemical activity of the particles in their en-,vironment and the relative susceptibility ofthe receiving material. Particles may causechemical deterioration either by acting ascondensation nuclei for the retention of ad-sorbed gases or harmful acids, or by theirown innate corrosive action.
In the following sections it will be seenthat particulate air pollution plays an impor-tant role in the corrosion of metals; in thesoiling, damage, and erosion of coatings andpainted surfaces, building stones, marble,and other building materials; and in the soil-ing and degradation of textiles.
B. EFFECTS OF PARTICULATE MATTERON METALS
Atmospheric particles may accelerate thecorrosion of iron, steel, and various nonfer-rous metals.
Metals are generally resistant to attack indry air,' and even clean moist air does notcause significant corrosion .I, 2 Furthermore,inert dust and soot particles without sulfurcompounds as constituents do not of them-selves cause marked corrosion.1.5 Particlesmay, however, contribute to accelerated cor-rosion in two ways.* First, they may be in-trinsically active, and secondly, although in-active, they may be capable of absorbing oradsorbing active gases (such as SO2) fromthe atmosphere.
Those partticles which are inactive andhave negligible capacity for absorption oradsorption have little effect other than, thatof acting as droplet nuclei in the atmosphere.For example, silica particles do not acceler-ate the rate of metal corrosion even in thepresence of 802. On the other hand, char-coal (carbonaceous) particles in atmos-pheres with relative humidities below 100percent cause a large increase in the rate ofcorrosion in the presence of SO2 traces, pre-sumably through the local, concentration ofthe gas by adsorption., The laboratory re-search which led to these findings was basedon particulate concentrations of 0.4 mg /cm=(equivalent to 0.3 tons /mil) and abnormallyhigh SO2 concentrations of 100 ppm.
Active hygroscopic particles such as sul-fate and Chloride salts and sulfuric acid aero-sol serve as corrosion nuclei. Their presencein the atmosphere can initiate corrosion, evenat low relative humidities.5 Laboratory stud-ies of bare and varnished steel test panels,properly polished and degreased, and theninoculated with finely divided particles ofvarious substances such as are commonlyfound in the atmosphere, were conducted byPreston and Sanya1.5 Particles of chloride,sulfate, chromate, and oxide salts, and boilerand flue dusts were used. The metal test pan-els were exposed to atmospheres of pureclean air and of air containing SO2 at vari-ous humidities, and the resulting corrosionwas measured. Filiform corrosion, character-ized by a filamental configuration, the pYi-mary phase in electrolytic corrosion, wasnoted in all cases. Corrosion rates are lowwhen the relative humidity is below 70 per-cent, but they increase at higher humidi-ties.,. In most of the cases in this study,corrosion increased with increased humidityeven in clean air. The addition of traces of
65
."41 1176
SO2 to the test atmosphere greatly increasedthe rate of corrosion in all instances.5
Field experiments show that the rate ofcorrosion of various metals is accelerated inurban and industrial areas because of thegreater atmospheric concentrations of bothparticulate matter and sulfur compounds.Standardized open-hearth iron specimens,after exposure for one year at a number ofdiverse locations throughout the world, wereobserved by Hudson' to have a manifoldvariation in weight loss. Iron specimens ex-posed for one year to desert and arctic en-vironments, the least polluted areas, werethe least corroded, i.e., had the smallestlosses in weight. Those speimens exposed atheavily-polluted urban industrial sites werethe most corroded, more so than similarspecimens exposed at many marine and trop-ical locations, Table 4-1. Hudson, Figure 4-1,also correlated the rate of rusting of mildsteel specimens and dustfall levels for fourdiverse areas, from a heavily industrializedarea in Sheffield, England, to a rural area(Llanwrtyd Wells). The iron specimens cor-roded four times as fast in the polluted in-dustrial atmosphere as they did in the ruralatmosphere.
COmmittee B-6 of the American Societyof Testing Materials (ASTM) s, 9 studied cor-
0 16 32. 48 64 80DUST FALL, TONS / M12 MONTH
96
FIGURE 4-1. Plot of Rate of Rusting Versus Dust-fall at Four Locations.' (The figure plots the rateof rusting of mild steel versus dustfall, and showsthat corrosion is four times as rapid in an in-dustrial area (Sheffield) as it is in the rural area(Llanwrtyd Wells) ).
rosion rates of steel and zinc panels exposedfor one year at several locations in the UnitedStates. The relative corrosivities of variousatmospheres at 19 sites were compared tothat of the rural site of State College, Penn-sylvania, which was used as a base. Thisstudy (Table 4-2) confirms Hudson's ob-servations that industrial locations with
Table 4-1.CORROSION OF OPEN HEARTH IRON SPECIMENS IN DIFFERENT LOCATIONS.'
Location Type of atmosphereAnnualweightloss, g
RelativeC0170.sivity
Khartoum, Sudan Dry inland 0.16 1Abisko, North Sweden Unpolluted 0.46 3Aro, Nigeria Tropical inland 1.19 8Singapore, Malaya Tropical marine 1.86 9Basrah, Iran Dry inland 1.39 9Apapa, Nigeria Tropical marine 2.29 16State College, Pa., USA Rural 8.76 26Berlin, Germany Semi-industrial 4.71 82Llanwrtyd Wells, British Isles Semi-marine 6.23 86Calshot, British Isles Marine 6.10 41Sandy. Hook, N.J., USA Marine-mmi-industrial 7.84 60Congella, South Africa Marine 7.84 60Motherwell, British Isles Industrial 8.17 66Wcolwich, British Isles Industrial 8.91 60Pittsburgh, Pa., USA Industrial 9.66 66Sheffield Univ., British Isles Industrial 11.63 78Derby South End, British Isles Industrial 12.06 81Derby North End, British Isles Industrial 12.62 84Frodingham, Britisii Isles Industrial 14.81 100
66
high concentrations of particles and of ox-ides of sulfur are more corrosive to steel andzinc than less industrialized areas. As shownin Table 4-2, steel specimens corroded in oneyear approximately 3.1 times as much inNew York City (spring exposure) and 3.3times as much in Kearny, New Jersey, assimilar specimens at State College, Pennsyl-vania. Zinc specimens corroded 3.6 and 2.6times as much in New York City (spring ex-posure) and Kearny respectively, as similarspecimens exposed at State College. Bothsteel and zinc specimens in New York City(fall exposure when the particle and SO
concentrations in the atmosphere are greaterthan in spring) corroded 6.0 and 3.7 times asmuch respectively as similar steel and zincspeciments at Sate College." The authors ofthe resulting papers did not give mean con-centrations of suspended particulate matterfor the various locations; but approximateconcentrations, based on NASN measure-ments 10 made after the corrosion studies, aregiven here. Based on Table 4-3, a town thesize of State College, Pa., could have a meansuspended particulate-matter level of 60 14/m3 to 65 pg/ms. The mean suspended par-ticulate matter concentrations were 176
Table 4-2.-CORROSIVITY OF ATMOSPHERES TOWARDS STEEL AND ZINC AT SELECTEDLOCATIONS RELATIVE TO THAT AT STATE COLLEGE, PENNSYLVANIA .°
Location Type of atmosphereRelative corrosivityof one-year test for
Steel Zinc
Norman Wells, N.W.T., CanadaEsquimalt, Vancouver Is., CanadaSaskatoon, Sask., CanadaPerrine, Fla
Polar-RuralRural-MarineRuralRural
0.030 . 60 . 60 . 9
0.40.40.51.0
State College, Pa Rural 1.0 1.0Ottawa, Canada Semi-Rural 1.0 1.2Middletown, Ohio Semi-Industrial 1.2 .9Trail, B.C., Canada Semi-Rural 1.4 1.6Montreal, Que., Canada Industrial 1 . 6 2.2Halifax, N.S., Canada Rural-Marine 1 . 5 1.6South Bend, Pa Semi-Rural 1 . 5 1.6Kure Beach, N.C., 800-ft site Marine (800 ft from ocean) 1 . 8 1.7Point Reyes, Calif Marine_ 1.8 1.8Sandy Hook, N.J Industrial-Marine 2.2 1.6New York, N.Y. (spring exposure) Industrial 8.1 3.6Kearny, N.J Industrial 3.3 2.6Halifax, N.S., Canada Industrial -Marine b 3 . 8 .18.0New York, N.Y. (fall exposure) _ Industrial 6.0 3.7Daytona Beach, Fla Marine 7.1 '2.6Kure Beach, N.C., 80-ft site Marine (80 ft from ocean) 18.0 6.7
While test site is 1600 ft. from brackish water, prevailing winds are from inland and prevent deposition of saltwater spray.
b Test site is near a smokestack; prevailing winds blow fumes over the test site.
Table 4-3.-THE CORROSION RATES OF METALS IN VARIOUS LOCATIONS:
Test Site
Corrosion rate, mil/year
Nickel200
Monel Copperalloy 400
Altoona, Pa. (Heavy industrial-R.R.) 0.222 0.076 0.066New York, N.Y. (Urban-industrial) 0.144 0.062 0.064State College, Pa.. (Rural-farm) 0.0086 0.007 0.017Phoenix, Ariz. (Rural-semiarid) 0.0016 0.002 0.006
fig/ma in New York City and 131 fig/m3 atElizabeth, New Jersey, near Kearney," itshould be pointed out that there are signifi-cant differences in levels of gaseous pollution,particularly sulfur dioxide, between StateCollege and the larger industrial communi-ties. Consequently, the differences in corro-sion rates cannot be solely attributed to theeffects of 'particulates.
In Chicago and St. Louis, steel panels wereexposed at a number of sites, and measure-ments were taken of corrosion rates and oflevels of sulfur dioxide and particulates." InSt. Louis, except for one exceptionally pol-luted site, corrosion losses correlated wellwith sulfur dioxide levels, averaging 30 per-cent to 80 .percent higher than corrosionlosses measured in nonurban locations. Overa 12-month period in Chicago, the corrosionrate at the most corrosive site (mein SO2level of 0.12 ppm) was about 50 percenthigher than at the least corrosive site (meanSO2 level of 0.03 ppm). Sulfation rates in. St.Louis, measured by lead peroxide candle,also correlated well with weight loss due tocorrosion. Although suspended particulatelevels measured in Chicago with high-volumesamplers correlated with corrosion rates, acovariance analysis indicated that sulfur di-oxide concentrations had the. dominant in-fluence on corrosion. Measurements of dust-fall in St. Louis, however, did not correlatesignificaritl'ir with corrosion rates. Based onthese data, it appears that considerable cor-rosion may take -place (i.e., from 11 percentto 17 percent weight loss in 'steel panels) atannual average sulfur dioxide concentrationsin the range of 0.03 ppm to 0.12 ppm, andalthough high particulate levels tend to ac-company high sulfur dioxide levels, the sul-fur dioxide concentration appears to have themore important influence.
Comparative studies of the rates of cor-rosion of zinc-coated steel panels exposedto various community atmospheres were con-ducted by Committee B-3 of the ASTM.9 Thecorrosion rates of. zinc at four of the loca-tions over a six-year period are shown inFigure 4-2, as weight loss versus time. Foreach location, the corrosion rate is essential-ly constant with time. The atmosphere ofNew York City with greater concentration
i968 -( t
9
4cc
Si 30
2 SOUTHBEND, PA
1 2 3 4
EXPOSURE, YEARS
5 6
FIGURE 4-2. Weight Loss from Zinc Specimen as aFunction of Exposure Time' (The figure showsthe rate of corrosion of zinc at four locations inthe United States, and indicates that corrosion ismore rapid in industrial areas.)
of particles and sulfur oxides produces asteeper rate of corrosion of zinc than thatof Kearny, New Jersey, which is also heavilypolluted. Zinc corrodes at a greater ratein both industrial communities than in therural or semirural sites in South Bend,Pennsylvania, 'and State College, Pennsyl-vania.'
Studies of the effects of air pollution onthe atmospheric corrosion of three metals(nickel 200, Monel alloy 400, and copper)exposed to four diverse atmospheres (heavy-industrial, urban-industrial, rural-farm, andrural- semiarid) were conducted over a 20-year period.' Nickel 200 is 99.5 percent nickeland Monel 400 is essentially 30 percent cop-per and 70 percent nickel. Though thesemetals are relatively corrosion-resistant, itwill be noted from Table 4-3 that they are
corroded more in industrial atmospheresthan in rural ones. However, because of thecorrosion resistance of the metals, all of therates are relatively low when compared tothose for unalloyed iron or steel. In the in-dustrial locations, nickel 200 corroded atrates two to four times greater than Monel(nickel-copper) alloy 400, while in the rurallocations, its corrosion rate was about equalto that of Monel alloy 400, and only one-halfthe rate for copper. Even Monel 400, withits superior corrosion resistance, when usedas a gutter in an industrial installation, be-came pitted when the soot was permitted toaccumulate.9 Unburned carbon in the sootled to the formation of local galvanic cor-rosion cells. The result was premature per-foration and accelerated attack of the metalsheet.
Larrabee '2 confirmed that the corrosionresistance of steel is greatly improved by theaddition of small amounts of copper, or lowalloys of chromium, nickel, copper, and phos-phorus. The additional cost of such alloysteels when they are used to resist atmos-pheric corrosion is attributable to air pollu-tion.
Particles can cause corrosion of electronicgear of all types even where pervious metalsare used to minimize such corrosion. Elec-trical instruments and electronic componentsare factors of growing importance in thecomputer and missile industries, and alsomonitor and control an increasingly largeshare of manufacturing processes 18 Oily ortarry particles, commonly found in industrialand urban areas, are serious factors in thecorrosion and failure of electric contacts,connectors, and components."
Dust ditn act mechanically or chemically onelectric contacts. It can deposit on the sur-faces and interfere with electrical contactclosure, it can become imbedded in the: sur-faces of contacts, or -it can induce wear byabrasion if the contacts slide.", Hygro-scopic dusts, aciumulated on contacts, willabsorb water to form thin 'electrolytic filmswhich are 'corrosive "to ::base metals.9 If thecontact members are not of identical com-position, galvanic corrosion may, occur. The
avoided or minimized only by fabricating theelectrical contacts out of nonreactive metals,by encapsulation, or by air purification de-vices such as filters or by gas-absorbingchemicals. Any of these solutions to the prob-lem increases costs.
C. EFFECTS OF PARTICULATE MATTERON BUILDING MATERIALS
Building materials and surfaces are soiled,disfigured, and damaged by atmospheric par-ticles. Some of these stick to surfaces ofstone, brick, paint, glass, and compositionmaterials, forming a film of tarry soot andgrit which may or may not be removed bythe action of the rain. The result is a dingy,soiled appearance (Figure 4-3) , a loss inaesthetic attractiveness and, in many cases,a physical-chemical degradation or erosion ofthese surfaces.
In cities where large quantities of soot-providing fuel are burned, the problem isparticularly severe. Much .money and effort'have been.spent on sandblasting off the sootylayers which have accumulated on prominentbuildings in burning soot-produting fuelcities."-17 The tarry substances or carbona-ceous material resulting from inefficient com-bustion of soot-producing fuel are likely tohe sticky and also acidic;2 if not flushed offby rain they will adhere to surfaces and cor-.rode them over extended periodi of time."Smoke particles may also act as a reservoirfor adsorbed gasesi' such as S02., and harmfulacids, including sulfurous, sulfuric; and hy,,drochloric acids, as well as hydrogen sulfide.Theie materials cause the deteriontion ofmany of the less resistant tyes ol mason-
Buildings : in polluted areas bec me un-sightly quickly and require periodic :leaningand maintenance to remove the t trry as-
deposita:. In Washington D.C.. itwas found necessary to clean the si ioke andgrime from the new Supreme Court buildingeven before initial occupancy (in the mid-
': thirties) .14! While the soiling effect f soot isby fai the most eVident to the eye, if does notin itself cause the deterioration of buildingmaterial. The destruction is due to acids,
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D. SOILING AND DETERIORATION OFPAINTED SURFACES
Painted surfaces, walls, and ceilings ofhomes and other buildings are soiled by tarryand other particulate substances in the at-mosphere. Furthermore, there are both liq-uid and solid particles present in pollutedair in the form of fumes and mists of vary-ing chemical composition which react withpainted surfaces."." The damage done isboth . aesthetiC and material, and may affectnot only buildings but also paintings andother works of art.
Auto finishes have been observed to be-come pitted and stained by iron particlesdeposited on them from a metal grinding op-eration nearby,6 22 while chromic acid mistfrom an electroplating operation formed abrown stain on light colored cars and a"blushing" on darker shades of paint. Re-painting was required because the colorchanges were _not reversible by washing orpolishing.23.23 Cars parked near demolitionoperations of brick buildings have been se-verely dainaged by alkali mortar dust in thepresence of moisture." Characteristic pittingof painted surfaces is also caused by sodiumcarbonate particles from such industrialprocessing as soda ash manufacture.
Water soluble chlorides and sulfatesmostly the iron, copper, calcium, and zincsaltsare commonly found in particulatesamples from cities 2423.24 an& in rainwa-ter.23 These water-Soluble particles are. po-tential sources of osmotic blistering ofPainted surfaces. The effects on weatheringby small ,quantities of such particles havebeen examined 21 during laboratory studiesof accelerated aging of various paint panels.The presence of ..0:1 ppm of iron in the waterin the accelerated weatherapparatus pro-duced yellow staining, while 0.5 ppm of cop- -per produced severe brown staining. Thesesame effects may, be expected on natural ex-posure.",
Dust particles settling on wet varnish andpaint films Produce visible imperfections andreduction in the Plartriest1 remictfavirta .
tective coatings, two sets of metal panelswere coated with a varnish formulation un-der a "dust-free" apparatus, and then one setwas removed from the apparatus so that thevarnish films dried in contact with the lab-oratory air. The panels were then immersedin 3 percent aqueous sodium chloride forseven and one-half months. Where the var-nish film had dried in "normal" laboratoryroom air, considerable .rusting occurred onthe panels after six months of immersion; nocorrosion occurred on the panels dried in the"dust-free" environment. Clearly the dustparticles that settled on the films of the pan-els during the drying period were a pre-dominant factor in initiating corrosion of themetal."
The exteriors of buildings in industrialareas, when 'repainted, collect numerousblack specks on their surfaces even beforethe paint has dried." Within two to fouryears. depending on the degree of particleconcentration, these building exteriors aredistinctly soiled and require repainting."."
E. SOILING AND DEGRADATIONOF TEXTILES
Soiling of clothing, curtains, and othertextiles not only diminishes their aestheticappeal but also reduces their functional ef-fectiveness. A garment which soils readilywill not have the same user appeal as onewhich does not, even thoughits performancemay be equal in other respects. Economiccosts are therefore involved both in the extracleaning of garments which soil readily andin the development and manufacture of soil-resistant textiles.
The extent of soiling of textiles, such ascurtains, is influenced by various externalfactors such as temperature, relative humid-dity, and wind speed. and the specific sizeand characteristics of the atmospheric par-ticles. In addition, the degree of soiling is de-pendent on the construction and finish of thetextile material and the type of fiber fromwhich it is made.27
When large particles are deposited on theavifona' 44tzs 4.;...141"
as air sweeps through the intricate channelsbetween them, i.e., the material behaves as afilter. The soiling of curtains and flags is anillustration of this effect. Airborne particlescan also affect the cleanliness of yarns andfabrics during their manufacture.. Economicloss to textile manufacturers can occur unlesssuitable air filters are used in manufacturingplants." Laboratory studies by Rees," usinga dust circulating apparatus under controlledconditions; show that a closely woven fabricof low porosity .best resists soiling by air-borne particles.
If an exposed textile material acquires anelectrostatic charge, for example by friction,and is able to retain its charge, charged par-ticles of opposite sign will be attracted to it,thereby increasing its rate of soiling." Cel-lulose acetate and some of the synthetic tex-tiles acquire, by friction during spinning andweaving, electrostatic charges which, be-cause of the high insulating properties ofthese materials, are retained for a long peri-od of time. This results in troublesome "fog-marking," caused by attraction of airborneparticles to the charged textile."'
In laboratory investigations of the electro-static attraction of airborne particles to cot-ton textiles, Rees 27 found that soiling is morerapid when the fabric is charged than whenuncharged, and that the rate of soiling isincreased by raising the applied electric po-tential (which .increases the charge densityon the fabric). For any given potential, therate of soiling appears t6 be greater for apositively charged fabric specimen than fora negatively ,charged one.
The vulnerability of textile fabrics andfurnishings to the acid components of par-ticulate matter depends on the chemical Com-position of the textiles."' Cellulosic fibers,such as cotton; linen, hemp, jute, and man-made rayon are particularly sensitive to at-tack from such substances as sulfurous. andsulfuric acids, r while .animal fibers, such aswool and furs, are more'. resistant to' aciddamage.,
Curtains are particularly vulnerable to airpollutants, and often , deteriorate quicklyhanging at open windows, soiling' occurs tosnrn a airfarif.:. AVAITI whai; isrink.mia sis
filter for acid-laden dust and soot. Airbornemetallic iron and zinc particles, constituentsof city dust". 28' 29 are catalysts and pro-mote oxidation of sulfur dioxide to sulfuricacid, which may contribute to textile degra-dation. Curtains weakened by conditions ofexposure arising partly from atmosphericsoiling and acidity give way in a character-istic manner by splitting in parallel linesalong the folds where the greatest numberof particles accumulated.
F. SUMMARY
Airborne particlesincluding soot, dust,fumes, and mist can, according to theirchemical composition and physical state,cause a wide range of damage to materials.They may cause deterioration merely bysettling on surfaces and soiling them thuscreating a need for more frequent clean-ing which in itself weakens materials. Moreimportantly, they can cause direct chemi-cal damage to materials in two ways: First,through their own intrinsic corrosiveness,and secondly, through the action of corrosivechemicals- which they may have absorbedor adsorbed. Airborne particulates havebeen implicated in the corrosion of metalsand metallic surfaces; in the soiling, dam-age, and erosion of buildings and otherstructures; in the discoloration and destruc-tion of painted surfaces; and in the aestheticdegradation and damage of fabrics andclothing.
Metals ordinarily can .resist corrosion indry air alone, or even in moist clean air.Even inert dust or soot, in the absence ofactive 'chemical agents. has little effect onmetal surfaces. However, hydroscopic par-ticles commonly found in the atmosphere cancorrode metal' 'surfaces although no otherpollutants may be present. This was shownin laboratory studies in which steel test pan-els were dusted with varioui common par-ticulatea. -Although corrosion rates were lowat relative humidities under 70 percent, theytended to increase with increased humidity.The-addition of . sulfur dioxide to the lab-oratory air greatly, accelerated the rates ofcorrosion
T.
environments, the least polluted areas, toheavily polluted urban industrial sites. Sam-ples of iron, for example, have shown weightloss due to corrosion that is four timesgreater in industrial atmospheres than inrural atmospheres. Steel samples corrodedin one year 3.1 times as much in New YorkCity (spring exposure), where the particu-late concentration was 176 µg /m', as in therural atmosphere of State College, Penn-sylvania, where the mean concentrationcould be expected to range about 60 µg /meto 65 igg/m3. Steel samples exposed in NewYork in the fall of the year, when the par-ticulate and sulfur dioxide levels are higherthan in the spring, corroded 6 times fasterthan the samples at State College. Similarly,zinc samples exposed in New York corrodedabout 3.6 times as much as those at StateCollege, while zinc samples at Kearny, NewJersey, corroded. about 2.6 times as much(the concentration was 131 µg /m° at Eliza-beth, New Jersey, near Kearney).
It should be concluded, however, that thevariation in corrosion rites referred to aboveare due only to differences in particulatematter, since there are significant differ-ences in gaseous pollutant concentrations be-tween State College and the other areas.Even highly resistant metals have showncorrosion rates which are progressivelylarger over the following range of. environ-ments; (1) a rural semiarid site; (2) arural farm enviornment; (8) an urban in-dustrial area; (4)' a heavy industrial Area.In Chicago and St. Louis, steel panels wereexposed at a number of sites, and measure-ments were taken of corrosion rates and oflevels of sulfur dioxide and particulates. InSt. Louis, except for one exceptionally pol-luted site, corrosion 'losses correlated wellwith sulfur dioxide levels, averaging 30 per-cent to 80 ,percent higher than corrosionlosses measured in nonurban locations. .0vera 12-month period in Chicago, the corrosionrate at the most corrosive site (mean SO2leVel of 0.12 ppm)' was about 50 percenthigher than at the least corrosive site (meanSO2 level of 0.08 *T) . Sulfation orates inSi Trinigi mananivirl hap laanA 11 itlia tcmilla
levels measured in Chicago with high-vol-ume samplers correlated with corrosionrates, a covariance analysis indicated thatsulfur dioxide concentrations had the domi-nant influence on corrosion. Measurementsof dustfall in St. Louis, however, did notcorrelate significantly with corrosion rates.Based on these data,' it appears that consid-erable corrosion may take place (i.e., from11 percent to 17 percent weight loss in steelpanels) at annual average sulfur dioxideconcentrations in the range of 0.03 ppm to0.12 ppm, and although high particulate lev-els tend to accompany high sulfur dioxidelevels, the sulfur dioxide concentration ap-pears to have the more important influence.
PartiCles play a significant role in coiro-sion and damage to electronic equipmct ofall kinds, even when precious metals areused to minimize such effects. The contactsin electrical switches are vulnerable to chem-ical or mechanical action by, particulates.The particulates commonly found in indus-trial and urban atmospheres are serious fac-tors in the corrosion and failure of electricalconnectors and circuits.
The ability of particulates to damage andsoil buildings, sculpture, and other struc-tures is particularly great in cities wherelarge quantities of coal and sulfur-bearingfuel oil are burned. Particles may cause de-terioration to many types of masonry byacting as reservoirs for the harmful acidsgenerated by the combustion of these fuels.In addition to direct erosion and physicaldegradation of materials, particles stick tosurfaces- with which they come in contact,forming a film of tarry soot and grit whichmay or may not be removed by the actionof rain. The result is a dingy, soiled appear-ance, and much money and effort mustbe spent to sandblast off the sooty layers thataccumulate.
Particles alsOmay soil the painted sur-faces of walls, ceilings, and the exteriorsof homes and buildings, and, under certaincircumstances, may cause them to becomestained and pitted. Automobile finishes, forexample, have been daniaged by partiCulatematter 'emi +tod'.frnm volvt.
zinc saltsare commonly found in particu-late samples from cities and in rainwaterand may cause blistering and enhance theweathering of painted surfaces. Particlesmay settle on painted surfaces before thepaint has dried, thus producing imperfec-tions and reducing the ability of the paintto protect the surface. Such surfaces arelikely to soon require refinishing.
The soiling of clothing, curtains, and simi-lar textiles makes them unattractive and di-minishes their use. The extent of soilingis influenced by a number of factors, includ-ing the temperature, the relative humidity,and the wind conditions. Small particlesmay penetrate deep into the fibers of cur-tains hanging in open windows. Curtainsweakened by such exposure to atmosphericsoiling and acidity deteriorate in a charac-teristic manner. The vulnerability of tex-tile products to the acid components of air-borne particles also depends on the compo-sition of the material. Cellulosic fibers, forexample, such as cotton, linen, hemp, jute,and man-made rayon, are particularly sensi-tive to attack from such substances as sul-furous and sulfuric acids. In addition tothe aesthetic degradation and the nuisancecreated by particulate matter, direct costsmay be associated with the increased rateof deterioration of textiles, the extra clean-ing required, and the manufacturing ex-penses for fabrics that are more resistant toair pollution.
G. REFERENCES
1. Sheleikhovskii, 'G. V. "Smoke Pollution ofTowns." Akademiya Kommunal'nogo Khzyaistvaim. K. D. Pamfilova. Academy of Municipal Econ-omy im. K. D. Pamfilova. Izdatel'stvo Mini-sterstva KomMunal'nogo Khozyaistva RSFSR,Moskva-Leningrad, 1949. (Translated from Rus-sian and Published for the National ScienceFoundation, Washington, D.0 by the Israel Pro-gram for Scientific Translations, Jerusalem,1961.) ,
2. Greenburg, L and Jacobs, M. B. "CorrosionAspects of Air Pollution." Am. Paint J., Vol. 39,pp. 64-78, 1955.
a Vernon, W. H. J. "The Corrosion bi Metals." `J.Roy. Soc. Arts, Vol .' 97, pp. 578-610;1949
4. Vernon. W Fr T «A
3.) Trans. Faraday Soc., Vol. 31, pp. 1668-1700.1935.
5. Preston, R. St. J. and Sanyal, B. "AtmosphericCorrosion by Nuclei." J. Appl. Chem., Vol. 6. pp.28-44, 1956.
6. Tice, E. A. "Effects of Air Pollution on the At-mospheric Corrosion Behavior of Some Metalsand Alloys." J. Air Pollution Control Assoc., Vol.12, pp. 533-559, 1962.
7. Hudson, J. D. "Present Position of the CorrosionCommittee's Field Tests on Atmospheric Cor-rosion (Unpainted Specimens)." J. Iron SteelInst., Vol. 148, pp. 161-215, 1943.
8. Larrabee, C. P. and Ellis, 0. B. "Report of aSubgroup of Subcommittee VII on Corrosivenessof Various Atmospheric Test Sites as Measuredby Specimens of Steel and Zinc. Committee B-3,American Society for Testing Materials." Am.Soc. Testing Mater. Proc., Vol. 59, pp. 183-201,1959.
9. Copson, H. R. "Report of Subcommittee VI. Com-mittee B-3, American Society for Testing Mate-rials." In: Corrosion of Nonferrous Metals Sym-posium, Am. Soc. Testing Mater., Spec. Tech.Pub. 175, 1955.
10. "Air Pollution Measurements of the NationalAir Sampling Network (Analysis of SuspendedParticulates, 1957-1961)." U.S. Dept. of Health,Education, and Welfare, Div. of Air Pollution,Washington, D.C., 1962.
11. Upham, J. B. "Atmospheric Corrosion Studies inTwo Metropolitan Areas." J. Air Pollution Con-trol Assoc., Vol. 17, pp. 398-402, 1967.
12. Larrabee, C. P. "Effect of Composition and En-vironment on Corrosion of Iron and Steel." Am.Soc. Metals, pp. 30-50, 1956.
13. Antler, M. and Gilbert, J. "The Effects of AirPollution on Electric Contacts." J. Air PollutionControl Assoc., Vol. 13, pp. 405-415, 1963.
14. Williamson, J. B. P., Greenwood, J. A. and,Harris, J. "The Influence of Dust Particles onthe Contact of Solids." Proc. Roy. Soc., Ser. A(London), Vol. 237, pp. 560-573, 1956.
15. Carey, W. F. "Atmospheric Deposits in Britain:A Study in Dinginess." Intern. J. Air Pollution,Vol. 2, pp. 1-26, 1956.
16. Meller, H. B. and Sisson, L. B. "Effects, of Smokeon. Building Materials." Ind. Eng. Chem., Vol.27, pp. 1309-1312, 1935.
17.' Le Clerc, E. "Economic and Social Aspects ofAir Pollution." In: Air Pollution (World HealthOrganization), Columbia University Press, NewYork, 1961, pp: 279-291.
18. Yocom, J. E. "The Deterioration of 'faterials inPolluted. Atmospheres." J. Air Pollution ControlAssoc., Vol. 8, pp. 203-208, 1958.
'19. Cartwright; J. Nagelschmidt, G, and SkidMore,J. W. '"The Study of Air Pollution with tha
20. Giles, C. H. "Adsorption. II. In Air Pollution andin Natural Processes." Chem. Ind. (London), Vol.19, pp. 770-781, 1964.
21. Holbrow, G. L. "Atmospheric Pollution: ItsMeasurement and Some Effects on Paint." J. OilColour Chemists Assoc., Vol. 45, pp. 701-718,1962.
22. Fochtman, E. C. and Langer, G. "AutomobilePaint Damaged by Airborne Iron Particles." J.Air Pollution Control Assoc., Vol. 6, pp. 243-247,1957.
23. Tabor, E. C. and Warren, W. V. "Distribution ofCertain Metals in the Atmosphere of SomeAmerican Cities." Arch. Ind. Health,. Vol. 17, pp.145-151, 1958.
24. Waller R. E., Brooke, A. G. F., and Cartwright,J. "An Electron Miscroscope Study of Particlesin Town Air." Intern. J. Air Water Pollution,Vol. 7, pp. 779-786, 1963.
25. Graff-Baker, C. "The Effect of Dust Particles onthe Electrical Resistance and Anti-CorrosiveProperties of Varnish and Paint Films." J. Appl.Chem., Vol. 8, pp. 500-598, 1958.
26. Parker, A. "The Destructive Effects of Air Pol-lution on Materials." The Sixth Des VoeuxMemorial Lecture. (Presented at the Annual Con-ference of the National Smoke Abatement Soci-ety, Bournemouth, England, September 28,1955.)
27. Rees, W. H. "Atmospheric Pollution and Soilingof Textile Materials." Brit. J. Appl. Phys., Vol.9, pp. 301-305, 1958.
28. Petrie, T. C. "Smoke and the Curtains." Smoke-less Air, Vol. 18, pp. 62-64, 1948.
29. Tebbens, B. D. "Residual Pollution Products inthe Atmosphere." In: Air Pollution, Chapter 2,Vol. 1, 1st edition, A.C. Stern (ed.), AcademicPress, New York, 1962, pp. 23-40.
Table of ContentsPage
A. INTRODUCTION 791. The Role of Economic Analysis 792. Gross Estimates 80
B. EARLY ECONOMIC STUDIES 811. Pittsburgh 812. Other Early Economic Studies 81
C. RECENT EFFORTS 811. Household Effects 812. Property Value Studies 833. Productivity Studies 84
D. SUMMARY 84E. REFERENCES 85
List of FiguresFigure5-1 Maintenance Frequency as a Function of Particle Concentration in
the Upper Ohio River Valley and the National Capital Area (forHouseholds of Above-average Income) 82
List of TablesTable
5-1 Estimated Costs Due to Air Pollution (Mellon Institute PittsburghStudy) 81
5-2 Differences in Cleaning Costs Incurred at Steubenville and at Union-town 82
Chapter 5
ECONOMIC EFFECTS OF ATMOSPHERIC PARTICULATE MATTER
A. INTRODUCTION
1. The Role of Economic Analysis
It is, perhaps, misleading to cordon off theso-called economic effects of particulate pol-lutants from the effects which are the gristof this document. All of the effects discussedin this document have an economic dimen-sion. Some of the economic dimensions areeasier to measure than others. It is difficultto determine, for example, what is the valueof preserving the health, or indeed the life,of individuals adversely affected by pollu-tion. It is somewhat easier to discover dif-ferences in expenditure patterns attributableto the presence of air pollution.
Difficult or easy, such valuation is a logi-cally necessary part of the air quality stand-ards decision process. Communities desir-ous of a more favorable environment areconfronted with the need for .two bodies offact. First, there are the physical and tech-nological laws that govern the generation,transport, and control of air pollution. Sec-ond, there are the undesirable effects ofpollution on man and his environment. Fur-thermore, these two realities conspire to pro-duce a dilemma. On the one hand, if theundesirable effects of air pollution are tobe avoided, economic resources that mightotherwise be used to satisfy other worthycommunity objectives will have to be, usedfor air pollution control instead, and, theother objectives foregone. If, on the otherhand, all these other objectives are retained'undiminished, . the effects of a , polluted en-vironment must be endured. It is evidentthat some sort of balance must bOtruc.k.Precisely where this Wince is acUeved isa matter for the individual community todecide.
The tools of economic analysis can illu-minate the nature of this dilemma and can .even, with some qualification, indicate a wayout. It is sometimes suggested, for instance,that the monetary value of the undesirableconsequences of not controlling air pollutionbe balanced against the consequences of in-stituting control. This is the thrust of themuch-heralded cost-benefit analysis, underwhich the decision maker must consider theavailable alternatives and choose that whichseems most favorable. Comparisons aremade insofar as possible in monetary terms,with the dollar serving as a common denomi-nator. It is the purpose of this chapter toreview the as-yet-small body of literature onthe economic value of the effects listedthroughout this volume.
A major difficulty in assessing damagesdue to particulate air pollution lies in iso-lating the effects of particulates from thoseof other classes of air pollutants, such as sul-fur oxides, ozone, oxides of nitrogen, andothers, including odors. The present stateof the arts with respect to the measurementtransport, ambient dosages, and the short-term and long-term effects of the severalair pollutants in various concentrations,durations; and conditions, demands that in-creased attention, including an expandedresearch effort, .be given to the determina-tion of the effects of air pollution and theeconomic costs of these effects.
It is a major objective of research intothe economic effects of air pollution to estab-lish quantitative relationships between vary-ing levels of pollution and outcomes (theeffects of those levels) and 'ultimately toarrive at acceptable measures of the eco-nomic coats attributable to them. In turn,when such costs are averted thei become thebenefits of air pollution control.
2. Gross EstimatesA review of the physical effects cited in
previous chapters suggests the possibilityof estimating damage factors and costs ofdamages. The basic measurement procedureinvolves four steps:
1. Identification of nonoverlapping cate-gories of air pollution. damage;
2. An estimate of the total value of thecategory, regardless of the air pol-lution effects;
3. Determination of an air pollutiondamage factor incorporating assump-tions or knowledge of the relation-ships between the total size of thecategory and the damages due to airpollution; and
4. Application of this damage factor tothe total value of the category, inorder to estimate the damages dueto air pollution and those due to theparticular pollutant.
For example, one category of effects is thecorrosion of steel structures which necessi-tates painting. An estimate might be devel-oped along the following lines. The SteelStructures -,Painting Council, PittsburghPa., estimated the annual cost of corrosion-inhibiting coatings applied to steel struc-tures at $500 million in 1965.1* This figureis adjusted at an annual rate of increase of6 percent,, yielding a 1968 estimate of $590million.= The Council estimated that a largeproportion of the paint was applied becauseof factors such as humidity and chemicals.They suggested that particulate air pollu-tion may be responsible for, about 5 percent
, of the need. for corrosion-inhibiting paints.-This factor was used to determine damagesdue to air pollution and the cost of the paint,estimated at $29.5 million. Added to thisis the labor required to apply the paint.Labor is approximately 2.5 times' the costof the paint as shown fir the 1949 study byUhlig3** The total paint and labor gives
*Estimate suPplied on March 11, 1965; contacted?again on April 24, 1968; but no-further work hadbeen done:
**This 2.5 labor factor atill holds true, as cari beseen by comparing total recorded, household repairexpenditures yeraus eigienditurea for materials in re-cent years.' In 1963, .for.example, the ratio was 2.3;
a total estimate of $103 million per year asthe cost of painting steel structures becauseof air pollution.
Commercial laundering, cleaning, and dye-ing is another category of loss due to dirtyair. In 1963, commercial laundering, clean-ing, and dyeing costs amounted to $3,475million.' Between 1958 and 1963, these costswere increasing by 5 percent annually. Theadjusted figure for this category .for 1968thus becomes $4,350 million.
The Beaver Report found evidence sug-gesting that one-third of laundry costs inEngland were attributable to the effects ofair pollution.° A damage factor' for thiscategory for the United States for the costof commercial laundering, cleaning, and dye-ing due to air pollution becomes $870 million.
Transportation delays is another good ex-ample of an economic loss. Air pollution isa major cause of reduced visibility. TheCivil Aeronautics Board reported that in1962 low visibility resulting from smoke,haze, dust, and sand in the air possiblycaused 15 to 20 plane crashes.? Other costsof low visibility include travel delays, diver-sions, cancellations, and the cost of trans-portation to individuals- who wish to escapepolluted areas on weekend trips. Land trans-portation costs may well include similarlosses2In air travel alone, the total costs ofdiversion, cancellation delays, and crasheswere estimated at $803 million for 1960.8Today, the cost would be higher, If as littleas 5 to 10 percent is attributed to air pollu-tion, $40 to $80 million or more is involved.
Automobile washing is another example.Expenditures on automobile washingamounted to $143 million in 1963.8 This cate-gory grew by almost 10 percent per year be-tween 1958 and -1963. Extending this rateyields an estimate of $210 million for carwashing in 1968. The $210 million is in-creased by another 50 percent to $300 millionalso, to adjust for the fact that washing bythe car owner is not included in the lOwerfigure.
The largest proportion of automobilewashing is probably caused by particulateair pollution. A damage factor of 80 per-cept is assumed for car washing, and ex-penditures , for automobile lyashing/due to
the effects of air pollution would be about$240 million for 1968.
If this procedure could be repeated fornonoverlapping categories of damage dueto particulate air pollution, additional esti-mates of such damages could be developed.
B. EARLY ECONOMIC STUDIES
1. PittsburghOne of the first comprehensive surveys of
damage due to air pollution in the UnitedStates was conducted in Pittsburgh duringthe years 1912 to 1913 by the Mellon Insti-tute. The estimates in the Pittsburgh in-vestigation were based on economic lossesdue to dustfall and smoke and were obtainedthrough interviews of individuals. . Theitems of cost and the total cost to the com-munity were ascertained as shown in Table5-1.
The Mellon Institute investigators arrivedat an annual per capita cost of $20 in 1913.Health effects were not included; aestheticlosses at the time were judged to be $5 perperson above the $20.10
Table 5-1.ESTIMATED COSTS DUE TO AIR POL-LUTION (MELLON INSTITUTE PITTSBURGHSTUDY?
Causes of expenditure CostTo smoke maker:
Imperfect combustion $1,520,740
To individual :Laundry bills 1,500,000Dry cleaning bills 750,000
To household:'Exterior painting 330,000Sheet metal work 1,008,000Cleaning and renewing wall paper 550,000Cleaning and renewing lace curtains 360,000Artificial lighting 84,000
To wholesale and retail stores:Merchandise 1,650,000Extra precautions 450,000Cleaning 750,000Artificial lighting 650,000Department stores 175,000
To 'quasi-public buildings:Office buildings 90,000Hotels 22,000Hospitals 55,000
Total $9,944,740
2. Other Early Economic StudiesA comprehensive study of the economic
effects of air pollution in Great Britain isdescribed in the Beaver Report in 1954.°This study considered both direct costs andefficiency losses. The direct costs includedlaundry and domestic cleaning; the clean-ing, painting, and repair of buildings; thecorrosion of metals and consequent cost ofreplacement and of providing protectivecoverings; damage to goods; additional light-ing; and extra hospital and medical services.Efficiency losses were represented by theeffects on agriculture of damage to soil,crops, and domestic animals; interferencewith transport; and reduced human effi-ciency due to illness.
. Le Clerc, writing in 1961 about economiclosses due to air pollution, cited data fromFrance and Great Britain, as well as somegeneral data on economic losses in the UnitedStates. The foreign data were quoted inlocal monetary units, which have varied overthe years in relation to the value of the dol-lar. Even those figures relating to theUnited States are cited in the context ofthe value of the dollar at the time of study.Some of the data contained estimates onmedical services; others did not 11
In these two studies no attempt was madeto relate economic losses to the ambient par-ticle concentration.
C. RECENT EFFORTS
1. Household EffectsMore recent attempts to assess specific
economic losses due to air pollution havebeen made by Michelson and Tourin in theUpper Ohio River Valley and elsewhere.12-26The investigators made a comparative analy-sis of Steubenville, Ohio and Uniontown,Pennsylvania. The socioeconomic and cli-matic data were generally comparable,whereas the air pollution levels, using par-ticle concentration (µg /m3) as an index,were dissimilar. Uniontown had an annualaverage of 115 igg/m3, while Steubenirille hadan annual average of 235 igg/m3.
Six categories of possible loss were studiedin each community:
1. Outside maintenance frequencies ofhouses (cleaning painting, etc.) ;
2. Inside maintenance frequencies ofhouses and apartments (walls, win-dows, drapes, curtains, venetianblinds, carpets, and furniture);
3. Laundering and dry cleaning ofclothing (with distinction between
summer and winter maintenancepractices);
4. Maintenance of women's hair andfacial care;
5. Inside maintenance of offices (clean-ing and painting) ; and
6. Store operation and maintenance(cleaning, painting, and other main-tenance items; losses due to spoilageof merchandise).
Data from only the first four categorieswere used in the comparative analysis owingto the heterogeneity of the establishmentsinterviewed and the small number of re-spondents for the last two categories, nos.5 and 6. It will be noted that these itemsof cost are related for the most part to theeffects of particulate matter rather- than toall air pollutants.
For each loss category three tyPes of datawere sought:
1. Activity frequency;2. Incidence (i.e., the)proportion of the
population to which various frequen-cies were applicable) and
3. Socioeconomic characteristics (i.e.,household income, educational level).
Questionnaires were designed separately foreach 'area of activity to collect accurate in-formation on frequency of maintenance op-erationa. Although income data were ob-tained in steps of $2000, only two incomecategories. were used in the final compara-tive analysis: "less than $8000" and "over$8000." The maintenance frequency factorwas calculated, and the frequency factorswere converted into dollar values.
Table 5-2 shows the calculated extra percapita and _total costs incurred by Staben-vine as a result of air, pollution.
The Upper Ohio River study also includeda third city, Martins Ferry,- Ohio, where theparticle concentrations were roughly mid-way between those of . the first two cities.
aa
Table 5- 2.-- DIFFERENCES IN CLEANING COSTSINCURRED AT STEUBENVILLE AND AT UN,IONTOWN."
Gross costActivity Differences
(Steubenville over Uniontown)Per
Annual Capita*Outside maintenance of
houses $ 640,000 $17Inside maintenance 'of
houses and apartments 1,190,000 32Laundry and dryclean-
ing, 900,000 25Hair and facial care 370,000 10
Total $3,100,000 $84*Based on estimated 1959 population of 36,400.
The average frequency of maintenance op-erations in Martins Ferry fell almost pre-cisely midway between those in Steuben-ville and Uniontown.
The curve relating costs of air pollutionand suspended particle concentrations, thelatter being used as an index of air pollu-tion, was found by these investigators to beessentially a straight line. Using these data,the authors extrapolated the straight lineof Figure 5-1 back to the average particleconcentration of the rural stations of theNational Air Sampling Network (NASN).
4.5e .
o 4.01.
cc 3.5)-
3.0.DEw=2.5
c2.0
W
1.07a-a
.0.6.
O BASED ON TWO PILOT STUDIES(10 MAINTENANCE ITEMS EACH)
- BASED ON TOTAL OF 23 ITEMS(UPPER OHIO RIVER STUDY'DATA ONLY) 2
1 STEUBENVILLE2 MARTINS FERRY _3 UNIONTOWN4 SUITLAND5 ROCKVILLE6 FAIRFAX CITY
I III0 26 50 76 100 126 150 176 200 250 300MEAN ANNUAL SUSPENDED PARTICLES F° / m3)
FIGURE 5-1. Maintenance Frequency as a Functionof Particle Concentration in the Upper Ohio RiverValley and the National Capital Area (for House-holds of Above-average Income). (This figureshows that maintenance frequency increases al-most linearly with the mean suspended particleconcentrations.)
The mean annual rural station concentra-tion of suspended particulate matter for1959 to 1961 was 25 p/m3.
A similar investigation of comparativecosts due to air pollution was conducted byMichelson and Tourin in the metropolitanWashington, D.C., area in 1967. The char-acter of metropolitan Washington differsmarkedly from that of Steubenville, the lat-ter having much heavy industry (steel mills,etc.). The Washington pilot study was basedon a selection of families in private dwellingsonly.
Four communities of the Washington, D.C.area (Rociniille Maryland; Suit land, Mary-land; Hyattsville, Maryland; and FairfaxCity, Virginia)' were originally selected forstudy because they represented extremes inparticle concentrations for outlying areas.At the time, they all had a large proportionof middle-income families. The returnedquestionnaires were processed (according tothe replies) by income group. Since it wasexpected that families in the very low andvery high income brackets would be rela-tively insensitive to particulate pollution,only the data in the $10,000-to-$14,000bracket were utilized. Deficiencies in the airquality data for Hyattsville precluded its in-clusion in the analysis.
Results from the three suburban Wash-ington communities compared quite favor-ably with the results from the Upper. OhioRiver Valley study on the ten items whichwere common to both studies. Figure 5-1shows the relationship betweeri suspendedparticle concentrations and maintenance fre-quency ratio (urban/rural) for the twostudies combined, as well as for the UpperOhio River Valley study alone.
It may be noted that in both sets of datathe association between the maintenance fre-quency ratios sand suspended particulates istaken to be linear over the range of the ac-tual data, 'rather than an :expected levelingout of the "curve" at extremely high con-concentrations of particulates. Maintenancefrequency ratios were not translated intocosts in the suburban Washington communi-ties because of widely different socioeco-
lies not so much in the estimates of cost,which are likely to vary in place and time,but in the estimates of differences in main-tenance. It should be noted that the use ofcommon cost/maintenance operation has theeffect of understating the true difference inexpenditures for the items studied betweenthe two areas.
The Michelson-Tourin studies have sug-gested one approach to the problem of esti-mating the costs of some of the effects ofparticulate air pollution. The results of in-vestigations to date are highly suggestive ofthe existence of a significant relationship be-tween the costs of household and personalmaintenance and the existence of air pollu-tion.
A word of caution in the interpretationof these results is in order. It is well,knownthat causation and statistical correlation arenot one and the same. There are a numberof other factors, not investigated in thestudies of Michelson and Tourin, which couldbe highly correlated with air pollution, andwhich could be casually related to the fre-quency with which'. the various personal hy-giene and property maintenance routinestudied are performed. For example, highlyurbanized areas are likely to have both rela-tively high levels of air pollution and a rela-tive abundance of the materials and skillsnecessary, for the performance of hygieneand maintenance operations (e.g., dryclean-ing establishments, beauticians, etc.). Morework is needed to find out unambiguouslyjust what forces are operating.
2. Property Value StudiesIn 1967 the results of investigations into
the effect of air pollution on property andother values in St. Louis, Syracuse, andPhiladelphia were published in a book byDr. Ronald Ridker entitled Economic Costsof Air PollutionStudies in Measurement."The studies were somewhat inconclusive;they dealt generally with air pollution effectsand did not attempt to isolate the effects ofparticulates. Nevertheless, the effort repre-sents an important methodological milestonebecause it describes some important attempts
suggestions for the guidance of investiga-tors. For example, in the chapter on "Soil-ing and MaterialDamage Studies," Dr.Ridker expresses pessimism with respect tothe value of additional studies based onanalysis of currently available data and, cit-ing the high cost of surveys, proposes asan alternative "a special type of experimen-tal approach to the gathering of the relevanteconomic information."
The recommended approach would seek toestablish the physical and biological effectsof various types and combinations of air pol-lution in varying concentrations and dura-tions. It would include study of the effectsof weather conditions and attempt to estab-lish predictive relationships that could de-scribe the amount of damage that would re-suit from specific exposure conditions. Theresulting damage functions could then besubjected to economic analysis in an effortto translate effects into costs.
Ridker's studies of air pollution and prop-erty values were limited to cross sectionstudies. They tended to show an inverse re-lationship between property values and airpollution levels as measured by mean valuesfor sulfation rates.
Other investigato4s, including T. D.Crocker," have demonstrated that the dif-ference in land value between a polluted anda nonpolluted area is an appropriate measureof potential gain from an abatement policy.
The results of property-value studies ap-pear encouraging in that they are a step inthe direction of defining a function relation-ship between reductions in air quality andeconomic loss. They supplement the studiesof effects of air pollution described previ-ously.
3. Productivity StudiesMany feel and some are convinced that
air pollution, and especially the combinationof suspended particulates with sulfur di-oxide, is associated with an increasing inci-dence of lung and respiratory ailments andheart disease."
To the extent that particulate air pollu-tion affects the respiratory tract and pro-duces or contributes to illness among theworking population, it may substantially re-duce human productivity and result in eco-
84 .,.
nomic losses. Economic losses would resultfiom work-loss days, reduced worker pro-r!activity, and a shortened productive worklife. At this time, it is not possible to domore than speculate about the possible mag-nitude of this possibly significant economicloss.
Efforts to provide useful economic esti-mates of the effects of disease have long beena major problem for economists. Neverthe-less, estimates have been made for a numberof diseases and agreement appears to be de-veloping on measurement methods. Themost economically useful measure of theeffects of reduced productivity would be thecapitalized value or the; present discountedvalue of gross lost production.". 22 Progressis reported in methods of valuing a humanlife, apart from livelihood. All efforts to con-struct acceptable estimates of the costs ofpoor health or early death attributable to airpollution depend on the results of researchthat can establish dependable cause and ef-fect relationships.
D. SUMMARY
The cost of painting steel structures be-cause of air pollution, particularly due toparticulate matter, has been estimated atabout $100 million a year. The annual costof commercial laundering, cleaning, and dye-ing due to air pollution is estimated at $850million. The adverse effects of air pollutionon air travel were estimated minimally at$40-$80 million in 1960; obviously, theywould be greater today. Expenditures forcar washing, including washing by the car-owner involved, due to air pollution are esti-mated at about $250 million iit 1968. Thisassumes the principal cause of frequent carwashing is particulate air pollution. TheMichelson and Tourin studies, despite theirstated deficiencies, reveal a general relation-ship between levels of particulate air pollu-tion and increased frequency of householdmaintenance operations. Unfortunately, itis not readily possible to convert these re-lationships into cost relationships that wouldbe uniformly applicable to all communities.
Studies of air pollution and residentialproperty values, while limited by data avail-ability, strongly suggest that a statistically
4
significant inverse relationship may existbetween higher levels of particulate andother air pollution and residential propertyvalues.
Efforts to provide useful economic info-mation about the effects of air pollution(particulates) on human health and pro-ductivity losses are incomplete because theydepend on results of other research effortsaimed at the establishment of dependablecause and effects relationships.
It may be possible to develop acceptablegross estimates of air pollution damagebased on analysis within a group of non-overlapping damage categories, as suggestedin the introduction to this chapter. If suchefforts are carried out with care, they mayprovide useful guides to policy determina-tion. Considerably more attention needs tobe given to the physical and biological ef-fects of air pollution before definitive esti-mates of the economic costs of air pollutioneffects can be made.
Such estimates are not the final step, how-ever. It will then be necessary to determinethe costs averted (or benefits) by a par-ticular mechanism or. program of air pol-lution control, in relation to the costs ofcontrol.
E. REFERENCES1. Steel Structure Painting Council, Pittsburgh,
Pa., Correspondence dated March 11, 1965.2. "Statistical Abstract of the United States:
1967." 88th edition, U.S. Bureau of the Census,Washington, D.C., 1967, Table 1067.
3. Uhlig, Herbert H., "The Cost of Corrosion tothe United States." Chem. Eng. NeNS, Vol. 27,pp. 2764-2767, 1949.
4. "Statistical Abstract of the United States, 1967."88th edition, U.S. Bureau of the Census, Table1193.
5. "U.S. Census of Business: 1963, Selected Serv-ices." Vol. 6, U.S. Dept. of Commerce, Washing-ton, D.C., 1963, Table I.
6. "Committee on Air Pollution Report, A Reportto the Minister of Housing and Local Govern.ment, Sir Hugh Beaver, Chairman." Her Majtesty's Stationery Office, London, 1954.
7. "The Polluted Air We Breathe." American Fed-erationist, Vol. 71(2), pp. 6-11, 1964.
8. Fromm, Gary, "Civil Aviation Expenditures,"In: Measuring Benefits of Government Invest-ments, The Brookings Institution, Washington,D.C., 1965, Table 2.
9. "U.S. Census of Business: 1963, Selected Serv-ices Area Statistics," Vol. 7, U.S. Dept. of Com-merce, WashingtOn, D.C., 1963, Table 1-8.
10. O'Connor, J J., Jr. "The Economic Cost of theSmoke Nuisance to Pittsburgh." University ofPittsburgh, Mellon Institute of Industrial Re-search and School of Specific Industries, Pitts-burgh, Pa., Smoke Investigation Bulletin 4, 1913.
11. Le Clerc, E. "Economic and Social Aspects ofAir Pollution." In: Air Pollution (World HealthOrganization), Columbia University Press, NewYork, 1961, pp. 279-291.
12. Michelson, I. and Tburin, B. "ComparativeMethod for Studying Cost of Air Pollution."Public Health Rept. Vol. 81(6), pp. 505-511,June 1966.
13. Michelson, I. and Tourin, B., "Report on Studyof Validity of Extension of Economic Effectsof Air Pollution Data from Upper Ohio RiverValley to the Washington, D.C. Area." PublicHealth Service Contract PH 27-68-22, Novem-ber 8, 1967.
14. Michelson, I. and Tourin, B., "Household Costof Living in Polluted Air Versus the Cost of Con-trolling Air Pollution in the Twin Kansas CitiesMetropolitan Area." Public Health Service Con-tract PH27-68-21.
15. Michelson, I. and Tourin, B., "Household Costof Living in Polluted Air in the WashingtonMetropolitan Area." Washington, D.C. Metro-politan Area Air Pollution AbateMent Confer-ence, January 1968:
16. Huey, N. "Economic Benefit from Air Pollu-tion Control." Preprint. (Presented at the NewYork-New Jersey Metropolitan Area Air Pollu-tion Abatement Activity, February 5, 1968.)
17. Ridker, R. G., "Economic Costs of Air Pollu-tion: Studies in Measurement." Frederick A.Praeger, New York, 1967.
18. Crocker, T. D., "Some Economic Aspects of AirPollution Control with Special Reference to PolkCounty, Florida." Research Report to U.S. Pub-lic Health Service, Grant AP-00389.
19. Committee on Pollution, National ResearchCouncil, "Waste Management and Control." AReport to the Federal Council for Science andTechnology, National Academy of Science, Na-tional Research Council, Washington, D.C., Pub.1400, 1966.
20. "Restoring the Quality of Our Environment."Environmental Pollution Panel, President's Sci-ence Advisory Committee, The White House,November 1965.
21. Weisbrod, B. A., "Economics of Public Health."University of Pennsylvania Press, Philadelphia,1961.
22. Klarman, 'H. E., "Syphillis Control Programs."In-: Measuring the Benefits of Government In-vestments, R. Dorfman (ed.), The BrookingsInstitution, Washington, D.C., 1965.
Chapter 6
EFFECTS OF ATMOSPHERIC PARTICULATEMATTER ON VEGETATION
Table of ContentsPage
A. INTRODUCTION 89B. EFFECTS OF SPECIFIC DUST ON VEGETATION 89
L Cement-Kiln Dust 89a. Direct Effects 89
(1) Nature of Dust Deposition 89(2) Range of Effects 91(3) Dust Components Involved 92
b. Indirect Effects 932. Flourides 933. Soot 944. Magnesium Oxide 945. Iron Oxide 946. Foundry Dusts 947. Sulfuric Acid Aerosols 94
C. EFFECTS OF DUSTS ON ANIMALS BY INGESTION OFVEGETATION 95
D. SUMMARY 95E. REFERENCES 96
Figure6-1 Bean Plants Dusted with Cement-Kiln Particles 906-2 Cement-Kiln Dust on Fir Tree Branches 916-3 Cement-Kiln Dust on Fir Tree Branches 91
List of Figures
88
Ij
Chapter 6
EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON VEGETATION
A. INTRODUCTION
Little is known abOut the effects of par-ticulate matter on vegetation and little re-search has been done on the subject. Therehas been far more research on gaseous pol-lutants, many of which' are readily recog-nized as serious toxicants to a variety ofplants. Published= experimental results,mostly from Germany, are confined princi-pally to settleable dusts emitted from thekilns of cement plants. There are a few re-ports on effects of fluoride dusts, soot. andparticulate matter from certain types ofmetal processing. Sulfuric acid aerosols havealso been studied in Los Angeles, where depo-sition of acid droplets has injured theleaves of vegetation. Most of the researchwas related to the direct effects of dusts onleaves, twigi, and flowers as opposed to in-direct effects from dust accumulation in thesoil. Because of the dearth of experimentalresults, the tenor of many reports is directedas much to the question, "Do dusts in facthave deleterious effects on plants?" as to thequestion of extent of injury. It is thus rea-sonable to anticipate some disagreement.Such information as there is refers to spe-cific dusts rather than to the conglomeratethat is usually measured as urban or ruraldustfall (Chapter 1). The various specificpollutant dusts and their injurious effectson vegetation are discussed in the followingsections.
B. EFFECTS OF SPECIFIC DUSTSON VEGETATION
1. Cement-Kiln DustCement-kiln dust is the dust contained in
waste gases from the kilns and is not deriveddirectly from processing of cement. It is ap-parent from some reports, however, that the
composition of wastes from different kilnsoperating at different efficiencies varies con-siderably, and at times the effluents may con-tain cementitious materials that more prop-erly belong in the finished product. Anotherimportant factor to consider is that literaturereports describing effects . of dust depositedon various plants in the field relate to kiln-stack materials, whereas experimental dustsapplied in laboratory or field studies weretaken from various collectors in the waste-gas system between the kiln and the stack.Differences in results that may be due to thisfactor have not been reconciled.a. Direct Effects
(1) Nature of Dust Deposition.Most ofthe reports concerning harmful effects ofcement-kiln dust on plants stress the factthat crusts form on leaves, twigs, and flow-ers. As early as 1909-1910 Peirce 1 andParish 2 noted in California that settled dustin combination with mist or light rain formeda relatively thick crust on upper leaf surfacesof affected plants. The crust would not washoff and could be removed only with force.The central theme about which Czaja "builds his case for harmful effects is the crustfOrmation in the presence of free moisture.He states that crust is formed because someportion of the settling dust consists of thz.calcium silicates which are typical of theclinker (burned limestone) from which ce-ment is made. When this dust is hydrated onthe leaf surface, a gelatinous calcium silicatehydrate is formed, which later crystallizesand solidifies to a hard crust. When the crustis removed, a replica of the leaf surface isoften found, indicating intimate contact ofdust with the leaf. The relatively thick crustformed from continuous deposition is con-fined to the upper leaf surface of deciduousspecies 18 completely encloses needles' of
89
conifers. Prolonged dry periods durisig thetime dust is deposited provide no opportunityfor hydration, and crusts are not formed.Dust deposits which are not crusted arereadily removed by wind or hard rain.
Dar ley 3 applied kiln dusts of particle sizeless than 10p at rates of 0.05 mg/en-0-day to0.38 mg /cm= -day to leaves for two to threedays in the laboratory. Water mist was ap-plied several times each day. Even thoughthe dust adhered to the leaf in a uniformlay6t, it did not appear to be crust-like,probably because the experiments were ofshort duration. Reduction in CO., uptake wasreported in these experiments.
Leaves of bean plants dusted for two dayswith cement-kiln dust of 8p to 20p size at
the rate of 0.47 mg /cm= -day and then ex-posed to naturally occurring dew were mod-erately damaged.' The injury (Figure 6-1)appeared as a rolling of the margins of theleaves, and some interveinal tissues werekilled. Leaves which were dusted but keptdry were not injured.
Photographs taken recently in Germanyby Dar ley (Figure 6-2 and Figure 6-3) showincrustations of cement-kiln dust on branchesof fir trees. Atmospheric levels of dust inthis area were probably in excess of 85 tons/mile2-month (0.1 mg/cm2-day). Incrusta-tions built up on the older twigs (Figure6-2) and caused needles to fall prematurely.Some of the twigs were dead and incrusta-tions were forming on the newest needles.
a
FIGURE 6-1. Bean Plants Dusted with Cement Kiln Particles. (a) Control Plant; (b) Dusted but Kept Damp;(c) Exposed to Natural Dew Formation After Each Day's Dusting.' (The photograph shows the effect ofdusting bean plants for two days witkphrticles (llit to 20p) from a cement kiln. The plant exposed to moistore (natural dew) and dust is moist affected. The dusting rate was 0.47 mg /cm' -day.)
90
,f01211116.
.16
FIGURE 6-2. Cement-kiln Dust on Fir Tree Branches.'(Incrustation has built up on the older twigs of afir tree exposed to a cement-kiln dustfall probablyin excess of 1 mg/ms-day. Needles have fallenprematurely.)
The net effect was a shortening of each suc-ceeding year's flush of growth. A dead treehad heavy incrustations on the branches(Figure 6-3).
(2) Range of Effeete.Peirce 1 demon-strated that incrustations of cement-kiln duston citrus leaves interfered with light re.quired for photosynthesis and reduced starchformation. This was later confirmed byCzaja 5 and Bohne 6 in a variety of plants.More recently, Steinhubel T compared starchreserve changes in undusted commaa hollyleaves and those dusted with foundry dust.He concluded that the critical factor in starchformation was the light absorption by thedust layer, and that the influence on tran-spiration or over-heating of leaf tissue was
FIGURE 6-3. Cement-kiln Dust on Fir Tree Branches'(Very heavy incrustation on a branch of a deadfir tree exposed to cement kiln dust (dustfall ratesprobably in excess of 0.1 mg/ine-day).)
of minor significance. Lecenier and Piquer(see Czaja 5) attributed the reduced yieldsfrom dusted 'tomato and bean plants to in-terference with light imposed by the dustlayer. Darley demonstrated that dust de-posited on bean leaves in the presence of freemoisture interfered with the rateof carbondioxide exchange, but no measurements ofstarch were made.
Czaja 5 stated that the hydration processof crust formation released calcium hydrox-ide. The hydrated crusts gave solutions ofpH 10-12. Severe injury of naturally dustedleaves, including killing of palisade and pa-renchyma milt, was revealed by microscopicexaminatio10e alkaline solutions pene-
;
91
trated stomata on the upper leaf surface,particularly the rows of exposed stomata onneedles of conifer species, and injured thecells beneath. Czaja 5 stated that. on broad-leaved species with stomata only on the lowerleaf surface, the alkaline solutions first sa-ponified the protective cuticle on the uppersurface, permitting migration o the solu-tion through the epidermis to the palisadeand parenchyma tissues. Typical alkaline pre-cipitation reaction with tannins, especiallyin leaves of rose and strawberry, was evi-dence that calcium hydroxide penetrated theleaf tissue. Bohne a described similar "cor-rosion" of tissues under the crust formed onoak leaves.
Czaja 8 has presented good histological'evi-dence that stomata of conifers may beplugged by dust, preventing normal gas ex-change by the leaf tissue. Uninhibited ex-change of carbon dioxide and oxygen by leaftissue is necessary for normal growth anddevelopment.
Bohne reported a marked reduction ofgrowth of poplar trees located about one milefrom a cement plant after production in theplant was more than doubled. The change ingrowth rate was determined by the width ofannual rings in the wood. Darley 3 observeda reduction of spring growth elongation onconifers in Germany, where the oldest nee-dles were incrusted. He also noted that plantswere stunted and had few leaves in the heav-ily dusted portions of an alfalfa field down-wind from a cement plant in California.Plants appeared normal in another part ofthe field where there was no visible dust de-posit. The dusted plants were also he /fly in-fested with aphis and it was not clear wheth-er the poor growth was due to the aphisfeeding or a direct effect of the dust. Ento-mologists suggested that the primary effectof the dust may have been to eliminate aphidpredators, thus encouraging high aphid popu-lations, which in turn cause poor plantgrowth because of their feeding.
Anderson e observed in New York thatcherry fruit set was reduced on the side ofthe tree nearest a cement plant. He demon-strated that the dust on the stigma preventedpollen germination. Schanbeck treated afield planting of sugar beets birekly with
t ; '92
2.5 g/m2 of dust. and observed that infectionby leaf-spotting fungus, Cercospora beticola,was significantly greater than in nondustedplots. He postulated that the physiologicalbalance was altered by dust increasing sus-ceptibility to infection.
Pajenkamp I' reviewed the unpublishedwork of several German investigators, someof whom had applied dust artificially to testplants, and stated that he was opposed to theview that dusts are harmful to plants. Heconcluded that depositions of from 0.75 g /m2-day to 1.5 g/m2-day (the latter amount rep-,resenting the maximum that might be foundin the vicinity of a cement factory) had noharmful effect on plants.
Raymond and Nassbaum 12 also stated thatcement dusts have little effect on wild plants.On the other hand, Guderian 18 and Wentzeldisagreed with Pajenkamp and stated thatthe limited evidence at best presented a con-tradictory picture and that Pajenkamp hadnot cited Czaja's earlier work a. 15.15 Theyalso pointed out that a deposit of 1.5 g/m2-daywas not maximum, since other workers hadfound up to 2.5 g/m2-day, and Bohne e hassince reported weekly averages of up to 3.8g/m2-day.
According to Czaja; Ewert concluded thatcement-kiln dust did not clog the stomata andthat the crust might have a beneficial effectas protection against transpirational lossesand a defense against fungi. Czaja also notedthat the interpretation of evidence by Ewertis open to question becau0e control plantswere heavily infested with flea beetles, whiletest plants were not.
(3) Dust Components InvolvedDetail onthe injury to be expected from certain ce-ment-kiln precipitator dusts was given byCm*" His work is based on comparisons ofchemical composition of dusts and resultantinjury to leaf cells of a sensitive moss plant,Mnium punctatum. A .cut leaf was mountedin water on a microscope slide, and dust wasplaced in contact with the water at the edgeof the cover slip. Any effect of the resultantsolution on leaf cells could be observed di-rectly. Eighteen of the dusts tested in thisway fell into the following categories:
1. No permanent injury to living cells,but some plasmolysis from the con -
-t
centration effect of the solution;2. Slight injury to readily accessible
cells, disruption of the cytoplism, anddisplacement of chloroplasts; and
3. Severe injury to all cells of the leaflet.Dusts were further described as follows:
group 1, pH of 9.5-11.5, a relatively high rateof carbonation, and intermediate amount(19-29 percent) of clinker. phase (calciumsilicates), and characterized by a high (36-79 percent) amount of secondary salts; group2, pH about 11, a high rate of carbonation, alower (13-16 percent) clinker phase andcharacterized by a high (81-85 percent) pro-portion of raw feed; group 3, pH 11-12, avery slow carbonation rate. and characterizedby a high (17-49 percent) clinker phase. Thegreater injury was thus related to the largeramounts of clinker phase, which in turn re-suite(' in higher and prolonged alkalinity. ButCzaja also pointed out that the compositionof dusts within the three groups was not con.:sistent, and that, although not yet demon-strated, the constituents of a given dust un-doubtedly influence one another.
In short-term experiments of two to threedays, Dar ley 3 dusted the primary leaves ofbean plants with fractionated precipitatordust obtained from Germany. The dust con-tained relatively high amounts of potassiumchloride, KCI. When a fine mist was appliedto dusted leaves, a portion of the leaf tissuewas killed (up to 29 percent) and it was pre-sumed that the action was due to KCI. Inlater experiments other fractions of thesame dust containing very little KCI causedan almost equivalent amount of injury, thusindicating that KCI was apparently not theonly factor involved. Current laboratory in-vestigations with different particle-size frac-tions of precipitator dusts collected aroundthe United States have demonstrated varyingdegrees of injury to bean leaves when dew isformed on the leaves. There appears to be noeffect from dry dusts alone. Inasmuch asthese dusts contain very little clinker phase,it is ap ;rent that some components otherthan thc.,e connected directly with hydrationof calcium silicates may also be responsiblefor injury.
(4) Indirect Effects.Pajenkampu re-
ported on unpublished work by Scheffer inGermany during two growing seasons, indi-cating that even considerable quantities ofprecipitator dust applied to the soil surfacebrought about no harmful effects and noother lasting effects on growth or crop yieldof oats, rye grass, red clover, and turnips.The dust had a content of about 29.3 percentlimestone (analyzed as lime, Ca0) and 3.1percent potassium oxide, K20. The maximumrate of deposit was 0.15 mg/cm2-day. Discon-tinuous dustings were made at 0.25 mg/cm2-day to give an average of 0.075 mg/cm2-day.In one year. the yield of red clover and theweight of turnips were higher in the dustedplots, although the yield of leaves in the lattercrop was reduced. Acid manuring of the soilappeared to increase yield but the interactionof dusting and manuring was not understood.
While Scheffer et al." found no direct in-jury to plants, they indicated that theremight be indirect effects through changes insoil reaction, which in time might impairyield.
Stratmann and van Haut IS dusted plantswith quantities of dust ranging from 0.fmg /cm= -day to 4.8 mg/cm2-day; dust fallingon the soil caused a shift in pH to the alkalineside, which was unfavorable to oats but fa-vorable to pasture grass.
2. FluoridesParticles containing flouride appear to be
much less injurious than gaseous flourides tovegetation. Pack et al." reported that 15percent of gladiolus leaf was killed whenplants were exposed four weeks to 0.79pg/m3fluoride as HF, but no necrosis developedwhen plants were exposed to fluoride aerosolaveraging 1.9 pg/m3 fluoride. Inasmuch as thematerial was collected from a gas streamWhich was treated with limestone and hy-drated lime, the aerosol was probably calciumfluoride. Moreover, when the accumulatedlevels of fluoride in leaf tissues were aboutthe same, whether from gas or particulate,injury from the latter was much less.
McCune et a/.2° reported an increase ofonly 4 mm tipburn on gladiolus exposed tocryolite (sodium aluminum fluoride dust),wherein the washed leaf tissue from thistreatment showed an accumulation of 29 ppm
fluoride. A 70-mm increase in tipburn wouldhave been expected if a similar accumulationhad occurred from exposure to HF. Exceptfor the slight tipburn noted above, theseauthors found that cryolite produced no vis-ible effects on a variety of plants nor did itreducf: growth or yield.
It is evident from the work of McCuneet at." that fluoride in plant tissue is accumu-lated from cryolite treatment, but the rate ofaccumulation is much slower than would beexpected from a comparable treatment withHF. For example, when comparing washedleaf samples, exposure of gladiolus to HF forthree days at 1.01pg/ms fluoride resulted inan accumulation of 26.4 ppm fluoride, where-as only 34 ppm was accumulated from an ex-posure to cryolite for 40 days at 1.7pg/m2fluoride: Pack et at" reported only one-thirdas much fluoride accumulated from particu-late matter as from gaseous forms.
Both the investigations cited above indi-cate that much of the particulate matter re.-mains on the surface of the leaf and can bewashed off, although that which remainsafter washing is not necessarily internalfluoride. Reduced phytotoxicity of particulatefluoride is ascribed in part to the inability ofthe material to penetrate the leaf tissue. Inaddition, McCune et al." suggest that in-activity of particles may be due to their in-ability to penetrate the leaf in a physiologi-cally active form.
3. Soot
Jennings 21 noted the suggeition that sootmay clog stomata and prevent normal gas ex-change but that most investigations tend todiscount this effect. Microscopic examinationfailed to show enough clogging of stomata onleaves of shade trees (broad-leaved species)to be significant. He further states that inter-ference with light can be more serious buthe offers no data from critical experiments tosubstantiate this theory.
A well-illustrated report by Berge22 showedplugged stomata on conifers growing nearCologne, Germany.. He also stated thatgrowth was adversely affected.
Necrotic spotting was observed on leavesof several plants where soot from a nearbysmokestack had entered a greenhouse." The
94
necrosis was attributed to acidity of the sootparticles. Plants outside the greenhouse werenot damaged, possibly because the particleshad been removed by rain before severe in-jury could occur.
4. Magnesium OxideThe possible indirect effect on vegetation
of magnesium oxide falling on agriculturalsoils was reported by Sievers.24 He notedpoor growth in the vicinity of a magnesite-processing plant in Washington. Experi-ments were designed to grow plants in soilcollected at various distances from the proc-essing plant, in normal soil and in soil towhich magnesium oxide was added. Suppres-sion of plant growth was demonstrated withthe high levels of magnesium. After the proc-essing plant ceased operation, injury to cropsin the area became less pronounced, indica-ting that the injurious effect was not a per-manent one.
5. Iron Oxide
Berge,25 in Germany, dusted experimentalplots with iron oxide at the rate of 0.15mg/cm2-day over one- to ten-day intervalsthrough the growing season for six years.The plots were planted with cereal grains orturnips, and effects of treatment on the pri-mary product, on straw, and on leaves werenoted. No harmful effect of the dust was de-tected on either crop. There was a tendencyfor improvement of yields of grain and tur-nip roots, but this was not statistically sig-
.nificant.6. Foundry Dusts
Changes in starch reserves were comparedin common holly leaves, untreated, andtreated with dusts emitted from foundryoperations.6 The critical factor was theamount of light absorbed by the dust layer,and the influence on transpiration or over-heating of leaf tissue was of minor signifi-cance. These observations agree with some ofthose reported above on the range of effectsof cement-kiln dust on vegetation.
7. Sulfuric Acid AerosolsThese particles too may settle on plants
and cause injury. They are not discussed here,'however, as the subject is covered in some
detail in Air Quality Criteria for SulfurOxides, a companion document.
C. EFFECTS OF DUSTS ON ANIMALS BYINGESTION OF VEGETATION
Particles which contain chemical compo-nents detrimental to animal health may beassimilated through ingestion of plant ma-terials. The toxic components may be ab-sorbed into the plant tissues or may remainas a surface contaminant on the plants. Whenevaluating the potential harm to animalsfrom ingeSted vegetation, both absorbed anddeposited particles should be considered.
Fluorosis in animals has been reportedfrom ingestion of vegetation covered with afluoride-containing particulate matter.26 In-jury occurs when absorbed plus depositedfluoride on the plants reached 40 ppm to 50ppm. Arsenic poisoning of cattle and sheephas occurred from ingestion of arsenic-con-taining particles settled on vegetation."
D. SUMMARY
There has been relatively little research onthe effects of particulate matter on vegeta-tion, and most of the experiments done todate have dealt with specific kinds of dustsrather than the conglomerate mixture nor-mally encountered in the atmosphere.
The significance of dusts as phytotoxicantsis not yet entirely clear but there is con-siderable evidence that certain fractions ofcement-kiln dusts adversely affect plantswhen naturally deposited on moist leaf sur-faces. Dry cement-kiln dusts appear to havelittle deleterious effect, but in the presenceof moisture the dust solidifies into a hard ad-herent crust which can damage plant tissueand inhibit growth. Modezate damage hasbeen observed on the leaves of bean plantsdusted at the rate of about 0.47 mg/cm2-day(400 tons /mil- month) for two days and fol-lowed by exposure to naturally occurringdew. Similarly, a marked reduction in thegrowth of poplar trees one mile from acement plant was observed after cement pro-duction was more than doubled. At levels inexcess of 0.1 mg/cm2-day (85 tons/mi2-month), incrustations have been observed onthe branches of fir trees, with the result thatneedles fell prematurely, shortening each
succeeding year's flush of growth. Althoughthe mechanism by which injury occurs is notentirely, understood, it is possible that thecrust intercepts the light needed for photo-synthesis and starch formation, causes alka-line damage to tissues, and prevents normalgas exchange in leaf tissues. Injury due tothe direct effect of high pH on cell constitu-ents does occur. Plugging of. stomata andreduced growth of trees may occur within ashort distance of cement plants.
It should be noted, however, that the harm-ful effect of cement dusts on vegetation is notfully substantiated and has been questionedby some workers. The controversy that sur-rounds this subject is not surprising in viewof the limited research to date. In addition,not all studies have been carried out underidentical conditions or with dusts of the samecomposition. Studies of the effects of cement-kiln dusts deposited on the soil also raisequestions. Some investigators repot noharmful effects at levels from 0.15 mg/cm2-day to 0.75 mg/cm2-day (130'tons/mi2-monthto 640 tons /mil- month), while others reportthat concentrations from 0.1 mg/cm2-day to4.8 mg/cm2-day (86(tons/mi2-month to 4,000tons /mil-month) cause shifts in the soil alka-linity which may be favorable to one crop butharmful to another.
Fluorides in particulate form are less dam-aging to vegetation than gaseous fluorides.Fluoride may be absorbed from depositionsof soluble fluoride on leaf surfaces. However,the amount absorbed is small in relation tothat entering the plant in gaseous form. Thefluoride from particulates apparently hasgreat difficulty penetrating the leaf tissue ina physiologically active form. The researchevidence suggests that few if any effects oc-cur on vegetation at fluoride particulate con-centrations below about 2tig/m2. Concentrations of this magnitude can be foUnd in theimmediate vicinity of sources of fluoride par-ticulate pollution, but they are rarely foundin urban. atmospheres. Fluorides absorbedor deposited on plants may be detrimental toanimal health. Fluorosis in animals has beenreported due to the ingestion of vegetationcovered with particulates containing fluo-rides. In a similar manner arsenic poisoningof cattle and sheep has occulTed from in-
95
k .0.410 4
gestion of arsenic-containing particulate thathad settled on vegetation.
Soot may clot stomata and may producenecrotic spotting if it carries with it a solubletoxicant, such as one with excess acidity.Magnesium oxide deposits on soils have beenshown to reduce plant growth, while ironoxide deposits appear to have no harmful ef-fects and may be beneficial. Sulfuric acidaerosols will cause leaf spotting. The levelsat which these materialsimay produce a toxicresponse are not well defined.
E. REFERENCES
1. Peirce, G. J. "An Effect of Cement Dust onOrange Trees." Plant World, Vol. 13, pp. 283-288,1910.
2. Parish, S. B. "The Effects of Cement Dust onCitrus Trees." Plant World, Vol. 13, pp. 288-291,1910.
3. Dar ley, E. F. "Studies on the Effect of Cement-Kiln Dust on Vegetation." J. Air Pollution Cun-trol Assoc., Vol. 16, pp. 145-150, 1966.
4. Dar ley, E. F. Unpublished data.5. Czaja, A. T. "Uber das Problem der Zementstaub-
wirkungen auf Pflanzen." Staub, Vol. 22, pp. 228-232, 1962.
6. Bohne, H. "Schadlichkeit von Staub aus Ziment-werken fur Waldbestande." Allgem. Forstz., Vol.18, pp. 107-111, 1963.
7. Steinhubel, G. "Zmeny v skrobovych rezervachlistov cezminy po umelom znecisteni pevnym po-praskom." Biologia, Vol. 18, pp. 23-33, 1962.(Abstract, in German, pp. 32-33, with the title:Veranderungen in den Starkereserven der Blat-ter der gemeinen Stechpalme nach einer kilnst-lichen Verunreinigung durch Staub.)
8: Czaja, A. T. "Uber die Einwirkung von Stauben,speziell von Zementofenstaub auf Pflanzen."Angew. Botan., Vol. 40, pp. 106-120, 1966.
9. Anderson, P. J. "The Effect of Dust from CementMills on the Setving of Fruit." Plant World, Vol.17, pp. 57-68, 1914.
10. Schonbeck, H. "Beobachtungen zur Frage desEinflusses von industriellen Immissionen auf dieKrankbereitschaft der Pflanze." Berichte derLawlesanstalt ftir Bodennutzungsschutz (Bo-chum), Vol. 1. pp. 89-98, 1960.
11. Pajenkamp, H. "Einwirkung des Zementofen-staubes auf Pflanze and Tiere." Zement-Kalks-Gips, Vol. 14, pp. 88-95, 1961.
13. Guderian, R. and Pajenkamp, H. "Einwiikangdes Zementofenstaubes auf Pflanzen und Tim."Staub, Vol. 21, pp. 518-519, 1961.
14. Wentzel, K. F. and Pajenkamp, H. "Einwirkungdes Zementofenstaubes auf Pflanzen und Tiere."Zeit. ftir Pflanzenkrankh, Vol. 69, p. 478, 1962.
15. Czaja, A. T. "Die Wirkung von verstaubtem Kalkund Zement auf Pflanzen." Qualitas Plant Mater.Vegeteaes, Vol. 8, pp. 184-212, 1961.
16. Czaja, A. T. "Zementstaubwirkungen auf Pflanzen : Die Entstehung der Zementkrusten." Quali-tas Plant Mater. Vegetabiles, Vol. 8, pp. 201-238,1961.
17. Scheffer, F., Przemeck, E., and Wilms, W. "Un-tersuchungen Ober den Einfluss von Zementofen-Flugstaub auf Boden and Pflanze." Staub, Vol.21, pp. 251-254, 1961.
18. Stratmann, H. and van Haut, H. "Vegetations-versuche mit Zementflugstaub." (Unpublished in-vestigations of the KohlenStoff-biologischen For-schungsstation) Essen, Germany, 1956.
19. Pack, M. R., Hull, A. C., Thomas, M. D., andTranstrum, L. G. "Determination of Gaseous andParticulate Inorganic Fluorides in the Atmos-phere." Am. Soc. Testing Mater., Spec. Tech.Pub. 281, 1959, pp. 27-44.
20. McCune, D. C., Hitchcock, A. E., Jacobson, J. S.,and Weinstein, L. H. "Fluoride Accumulation andGrowth of Plants Exposed to Particulate Cryo-lite in the Atmosphere." Contrib. Boyce Thomp-son Inst., Vol. 23, pp. 1-22, 1965.
21.
22.
23.
24.
25.
26.
12. Raymond, V. and Nussbaum, R. "A propos des 27.poussieres cimenteries et leurs effets surPhomme, NI plants, et les animaux." Pollut.Atmos. is), Vol. 3, pp. 284-294, 1966.
96
Jennings, 0. E. "Smi Ir. 'Try to Shade Trees."Proc. Nat. Shade t cee Co., l 10th, 1934, pp.44-48.Berge, H. "Luftverunreinigungen im RaumeKöln." Allgem. Forstz., Vol. 51-52, pp. 834-838,1965.
Miller, P. M. and Rich, S. "Soot Damage toGreenhouse Plants." Plant Disease Reptr., Vol.51, p. 712, 1967.Sievers, F. J. "Crop Injury Resulting from Mag-nesium Oxide Dust." Phytopathology, Vol. 14,pp. 108-113, 1924.Berge, H. "Emissionsbedingte Eisenstaube undihre uswirkungen auf Wachstum und Ertraglandwirtschaftlicher Kulturen." Zeit. Luft-vereinigung (Dusseldorf), Vol. 2, pp. 1-7, 1966.Shupe, J. L, Miner, M. L., Harrison,. L. E., andGreenwood, D. A. "Relative Effects of FeedingHay Atmospherically Contaminated by FluorideResidues, Normal Hay Plus Calcium Fluoride,and Normal Hay Plus Sodium Fluoride to DairyHeifers." Am. J. Vet. Res., Vol. 23, pp. 777-787,1962.
Phillips, P. H. "The Effects of Air Pollutants onFarm Animals." In: Air Pollution Handbook, P.L. Magill, F. R. Holden, and C. Ackley (eds.),McGraw-Hill, New York, 1956.
Chapter 7
SOCIAL AWARENESS OF PARTICULATE POLLUTION
Table of Contents.
01
PageA. INTRODUCTION 99B. THE STUDIES 99
1. St. Louis, Missouri 992. Nashville, Tennessee 1003. Birmingham, Alabama 1014. Buffalo, New York 101
C. SUMMARY 102D. REFERENCES 102
List of FiguresFigure7-1 Proportion of Population in St. Louis Stating Air Pollution Present
in Their Area of Residence, and Proportion of St. Louis PopulationBothered
7-2 The Level of Air Pollution Related to Public Opinion in Three In-come Groups (Nashville, Tennessee) 101
7-43 Radial Distribution from the Center of Nashville of Air PollutionLevels, Socioeconomic Status and Public Concern About Air Pollu-tion 101
100
981.07
Chapter 7
SOCIAL AWARENESS OF PARTICULATE POLLUTION
A. INTRODUCTION
The nuisance of air pollution is to someextent a subjective perception, and its signifi-cance is therefore influenced, to some extentby the way the public feels about pollution.Nevertheless, it is acceptable practice to con-clude that nuisance and levels of pollutionare related if it can be demonstrated that anuisance response by a sample population ispositively related to average levels of actualpollution. The development of such evidenceis difficult because public reaction probablyreflects pollution peaks rather than the meanvalue for an extended time period. This prob-lem has been considered by McKee 1 in a re-cent paper.
Several studies have attempted to assessthe annoyance to a population of communityair pollution, but not all have taken advan-tage of available aerometric data to establishthe relationships between air pollution levelsand attitudes and opinion among the affectedpopulation. The chief value of these surveyslies in demonstrating that a significant pro-portion of the public is aware of, and con-cerned about, air pollution, and is willing toact to abate the nuisance.; a One of the mostobvious indications of the nuisance of air pol-lution is citizen complaints. Generally speak-ing, the person who is willing to take thetime to telephone or write a complaint aboutair pollution is probably seriously irritated byit. And those who actually complain may rep-resent only the top of the iceberg. There aremany who may be irritated who will not com-plain because they do not believe complainingwill do any good. There are others, conspicu-ous by their absence, who have moved awaybecause of the effects of air pollution on theirhealth, or baesuse of the aesthetic degrada-tions of their neighborhood. Unfortunately,
very little work has been done in this partic-ular area of measuring the response of thepublic to the nuisance of air pollution.
It is important to note that application ofpresent control technology may result in amuch larger reduction in larger particlesthan in smaller particles. The remainingsmaller particles will not be as readily dis-cernible to the public, and awareness of par-ticulate pollution may diminish.
The effect of particulates on the total eco-logical system and man's enjoyment of hisenvironment cannot as yet be fully evaluated.
B. THE STUDIES
1. St. Louis, MissouriOne major investigation of the relation-
ship between public opinion and particulateair pollution concentrations is that conductedin the Greater St. Louis area.3.4 This areacomprises portions of St. Louis County, Mis-souri, and portions of Madison and St. ClairCounties, Illinois. It includes St. Louis, EastSt. Louis, and Granite City, and thus mostof the population residing in the St. Louismetropolitan area, as defined by the Bureauof the Census. Persons interviewed wereasked whether they believed that sir pollu-tion was present and whether they regardedit as a nuisance. The responses were relatedto the pollution level measured both as sus-pended particle concentration and as soilingindex. (See Chapter 1 for a discussion of thislatter measure of pollutant concentration.)Figure 7-1 shows the results obtained forboth questions in terms of suspended particleconcentrations. It will be seen that the popu-lation becomes aware of pollution before itregards it as a nuisance. Where the averageannual geometric mean of particles was 80µg /ma, better than 30 percent of the popula-
-10899
50 100 150
SUSPENDED PARTICLES, lig/m3(ANNUAL*GEOMETRIC MEAN)
FIGURE 7-1. Proportion of Population in St. LouisStating Air Pollution Present in Their Area ofResidence, and Proportion of St. Louis Popula-tion Bothered. (This figure presents the resultsobtained from interviews.)
2.00
tion indicated awareness of air pollution.Fifty percent and 75 percent of the surveypopulation were aware of air pollution in thearea where the average annual levels of par-ticulate matter were 120 pram' and 160 pg/m3respectively. None of the population ap-peared to be bothered by particle concentra-tions below 50 pg/m3, 10 percent of the popu-lation was bothered at a level of about 80pg/m3, 20 percent was bothered about 120pg/m3, 33 percent at 160 pg/m3, while 40percent regarded a concentration of 200pg/m3 as constituting a nuisance. The dataon the nuisance response in Figure 7-1 canbe expressed approximately in the form
yc-40.3x 14
over the range studied, where y is the per-centage of the population expressing dissatis-faction, and x is the annual geometric meanof suspended particle concentration in pg/I113.The equation assumes that the character ofthe pollution is the same for areas of bothhigh and low pollution.
2. Nashville, TennesseeA study by Smith et al..3 reveals the com-
plexity of public opinion surveys. The methodused was similar to that in other surveys:public opinion data were compared will aero-metric data from the nearest air samplingstation. One group of questions in the publicopinion survey dealth specifically with nui-
100
sance aspects of air pollution, asking re-spondents to indicate whether the outside ofthe house got too dirty, whether automobilesgot dirty too fast, and whether too much dustcollected on porches and window sills. An-other question, measuring "bother" by airpollution was embedded in a series of ques-tions relating to health, and responses to itshould not be compared directly with re-sponses of general concern and nuisance inother surveys. The proportion of affirmativeresponses to the question concerning toomuch dust and dirt on porch and window sillsshowed a clear increase with increasing par-ticle concentrations. The data do not, how-ever, permit a predictable quantitative state-ment of this responsibility.
Survey results indicated that up to 3.8percent of the respondents voluntarily ex-pressed awareness and concern about airpollution as a health problem; an extensionof the sample population of about 2,850 tothe total population indicated that this figureequated to approximately 9,000 residents.In response to a direct question, 23 percentof the respondentsor approximately 50,000residents, if the sample were projected to thetotal populationstated they were botheredin some way by air pollution. In response todirect questions, several specific non-healthaspects of smogsoiling, decreased visibility,odors, and property damagewere cited asaffecting from 18 percent to 51 percent ofthe respondents, or between 40,000 to 100,000of all residents, as based on the sample popu-lation. It was also concluded that the fre-quency of days of acute pollution had an ad-ditional influence on the proportion of peoplewho would express concern and annoyance.
The study indicated'some relationships be-tween level of concert and socioeconomicstatus. At high levels of air pollution, con-cern was greater among women of high socio-economic status than among women of lowsocioeconomic status, although at low levelsof air pollution, those of low socioeconomicstatus expressed more concern than those ofhigh status. There was also a relationshipbetween socioeconomic status and the dis-tance of residence from the center of Nash-ville (the more affluent living farther awayin general). Figures 7-2 and 7-3 together
109
demonstrate the interlocking relationship;Figure 7-2 uses arbitrary scales for bothvariables and should not be taken to indicatethe exact form of the relationships.
3. Birmingham, Alabama-Stalker and Robison 6 compared data from
21 air sampling stations with public re-sponses from a sample of 7200 households.Data were gathered only from people livingwithin one mile of an air sampling station.The investigators found that 10 percent ofthe population believed a nuisance existed ata seasonal (summer) mean suspended parti-cle concentration between 60 pg/m3 and 180pg/m3, and more than 30 percent of the popu-lation believed a nuisance existed at levelsbetween 100 pg/m3 and 220 pg/ms. The au-thors use their dustfall data to demonstratethat for each increment of 10 tons/mile-month another 10 percent of the affectedpublic would become concerned and considerthat level a general nuisance. Although thepublished data indicates that the relation-
CONCERN ABOUT AIR POLLUTION(ARBITRARY SCALE)
FIGURE 7-2. The Level of Air Pollution Related t,.)Public Opinion in Three Income Groups (Nash-ville, Tennessee).* (Figures 7-2 and 7-3 show theinterlocking relationships between several param-eters affecting public concern over air pollutionin Nashville. At high levels of pollution, concernis strongest in those of highest socio-economicstatus, while at low pollution levels, concern isgreatest among those of low status. This resultis possibly connected with the radial distance fromNashville at which persons of different socioeco-nomic status reside.)
ship probably is not linear, they do indicatethat the respondents clearly defined a nui-sance situation in their area of residence atannual mean dustfall values of 10 tonsjmile2-month or above.
4. Buffalo, New Yorkde Groot and Samuels 2 used two independ-
ent samples taken three years apart todetermine public opinion. Opinions were as-sessed against aerometric data from the near-est of nine air sampling stations. The meas-ure of public opinion wag4he percentage ofthe population considerine.air pollution aserious community problem. The investiga-tors counted only clear, unequivocal re-sponses; respondents who indicated uncer-tainty about the seriousness of the problemwere assigned to the "not serious" category.In :t.ffalo, as in Birmingham, there were ap-parent positive relationships between publicawareness and levels both of dustfall and of
foci
904\ AIR POLLUTION INDEX
80 -
70k-
SOCIO-ECONOMIC STATUSINDEX
30-
21)1-
INDEX OF CONCERN ABOUTAIR POLLUTION
10-
RADIAL DISTANCE FROM THE CENTER OF NASHVILLE,,TENN., MILES
.Ftsuits 7 -8. Radial Distribution from the Center ofNashville of Air Pollution Levels, SocioeconomicStates and Public Concern About Air Pollution.'
t 1101
suspended particles. There was also a posi-tive relationship between the frequency ofdays of acute levels of these pollutants andpublic opinion.
C. SUMMARY
Public opinion survey data in several citiesindicate a positive relationship between theconcern expressed about air pollution by apopulation and the actual levels of particulatepollution--used as an index of air pollution.In general, over the ranges studied, an in-creasing proportion of the population ex-presses dissatisfaction over air pollution asconcentrations of particulate matter increase.However, while the several studies agree, forthe most part, in this qualitative relationship,it is difficult to compare the studies quantita-tively. .Each study used different samplingschemes, questionnaire schedules, and meth-ods of interviewing. In addition, the socio-economic characteristics of the populationsampled varied from city to city. The St.Louis data has been singled out for quantita-tive expression because it showed the mostconsistent association between air pollutionand public awareness. However, it is in-tended to serve only as an example.
Over the approximate range 50 pg/m3 to200 pg/m3, the expression
y=0.3x 14relates roughly the percentage of concernedSt. Louis population, y, and the annual geo-metric mean suspended particle concentra-tion x (pg/m3). Thus, 10 percent of the studypopulation was bothered by air pollution inareas where the annual geometric mean valueof suspended particulates was about 80.pg/m3. About 20 percent of the study popula-tion was bothered in areas with an annualgeometric mean value of 120 pg/m and 33percent with a mean of 160 pg/m3. The re-sponses are probably associated with theshort term fluctuations in particulate levelswhich underlie any averaging time period.
Other studies show that when dustfalllevels exceeded an annual mean of 10 tons/miles-month, at least 10 percent of the af-
1.1.1102
fected population expressed concern about anuisance situation.
The available literature also indicates thatthe extent to which a population considers airpollution an annoyance is related to the fre-quency of days with acute pollution as wellas to the average level that the level of con-cern is related to socioeconomic status, andthat the population becomes aware of pollu-tion at particle concentrations lower thanthose at which they consider that it consti-tutes a nuisance.
In the St. Louis study, 30 percent of thestudy population were aware of pollution inareas where the annual geometric mean valueof suspended particulates was 80 pg/m3, 50percent in areas with 120 pg/m3 and 75 per-cent in areas with 160 pg/m3.
D. REFERENCES1. McKee, H. C. "Why a General Standard for Par-
ticulates?" (Presented at the Symposium on MrQuality Standards: The Technical Significance,156th National Meeting, American Chemical So-ciety, September 12, 1968.)
2. de Groot, I. and Samuels, S. W. "People and AirPollution : A Study of Attitude in Buffalo, NewYork. An Interdepartment Report." New YorkState Dept. of Health, Air Pollution ControlBoard, 1965. (See also de Groot, I., Loring, W.,Rihm, A., Samuels, S. and Winkelstein, W., sametitle, J. Air Pollution Control Assoc., Vol. 16, pp.245-247, 1966.)
3. "Public Awareness and Concern with Air Pollu-tion in the St. Louis Metrdpolitan Area." U.S.Dept. of Health, Education, and Welfare, Div. ofAir Pollution, Washington, D. C., May 1965. (Seealso Schusky, J., same title, J. Air Pollution Con-trol Assoc., Vol. 16, pp. 72-76, 1966.)
4. Williams, J. D. and Bunyard, F. L. "InterstateAir Pollution Study, Phase II Project Report,Vol. VIIOpinion Surveys and Air Quality Sta-tistical Relationships." 'U.S. Dept. of Health,Education, and Welfare, Div. of Air Pollution,Cincinnati, Ohio, 1966.
5. Smith, W. S., Schueneman, J. J., and Zeidberg,L. D. "Public Reaction to Air Pollution in Nash-ville, Tennessee." J. Air Pollution Control Assoc.,Vol. 14, pp. 418-423, 1964.
6. Stalker, W. W. and Robison, C. B. "A Methodfor Using Air Pollution Measurements andand Public Opinion to Establish Ambient AirQuality Standards." J. Air Pollution ControlAssoc., Vol. 17, pp. 142-144. 1967.
Chapter 8
ODORS ASSOCIATED WITHATMOSPHERIC PARTICULATE MATTER
112
Table of Contents ,
PageA. INTRODUCTION 105
B. EVIDENCE FOR THE ASSOCIATION OF ODOR WITHPARTICLES 105
C. HYPOTHETICAL MECHANISM FOR THE ASSOCIATION OFODOR WITH PARTICLES 1061. Volatile Particles 1062. Desorption of Odorous Matter by Particles 1063. Odorous Particles 107
D. COMMON ODOR PROBLEMS 107
E. SUMMARY 107
F. REFERENCES 108
List of TablesTable
8-1 Most Frequently Reported Odors 107
104
Chapter 8
ODORS ASSOCIATED WITH ATMOSPHERIC PARTICULATE MATTER
A. INTRODUCTIONThe human olfactory sense has the ability
to detect and respond to thousands of differ-ent materials or chemical compounds. Someodorants can be detected in concentrations aslow as one part per billion. Modern instru-mentation lacks both the selectivity and thesensitivity possessed by the olfactory sensefor the detection of many odorants.
Odorants in themselves may not cause or-ganic disease; however, the discomfort anddisagreeableness that may be brought aboutby obnoxious odors can cause some tempo-rary ill effects. The effects that border uponill health include lowered appetite, loweredwater consumption, impaired respiration,nausea, vomiting, and insomnia.
Particulate matter in itself is not consid-ered to be capable of directly stimulating theolfactory sense. However, this should not beinterpreted to mean that all airborne particu-late matter, as a pollutant category, is in-capable of stimulating the odor sense northat particles cannot be involved in the de-livery of the odorant to the receptor cells.There is evidence that some particles canstimulate the sense of smell because the parti-cle itself is volatile or because this particle isdesorbing a volatile odorant: There is alsospeculation 2 that some particulate matter iscapable of stimulating the sense of smell ".e-gardless of the mechanism of how particlesare involved in the stimulation of the olfac-tory sense, the important fact is that theydefinitely appear to be involved.
B. EVIDENCE FOR THE ASSOCIATIONOF ODOR WITH PARTICLES
The idea that odors are associated withparticles is supported by observations thatfiltration of particles from an odorous airstream can reduce the odor level. Rossano and
Ott 2 showed that the removal of particulatematter from diesel exhaust by thermal pre-cipitation effected a marked reduction inodor intensity. The precipitation method wasselected because it provides minimal con-tact between the collected .particles andthe gaseous components of the diesel ex-haust stream. Thus, effects that could beproduced by a filter bed, such as removalof odorous gases by absorption in the fil-ter cake, are eliminated. The observed odorreduction must, therefore. have resulted di-rectly from the removal of particulate mat-ter. The particles collected by Rossano andOtt were aggregates of spherical balls about0.04 to 0.05ii in diameter. Particulate matterfrom diesel exhaust collected on glass fiberfilters by Linnell and Scott' yielded a heavy"diesel" odor. Analysis of the particulatematter showed that it contained no acroleinor formaldehyde, although it did release NO2on being heated to 100°C. The authors con-clude that "no appreciable gas :chase con-centration changes for acrolein rif formalde-hyde will result from particulate removal."Other more or less casual observations on therole of particulate matter in community odornuisance problems appear occasionally in theliterature.'
A second piece of evidence that implicatesthe association of particles with odors is theproduction of a mild odor, sometimes de-scribed as "yeasty," in air that is passedthrough a bed of activated carbon. Turk andDownes 5 have shown that this odor is notproduced by any delectable desorption ofgaseous matter from the carbon, and thatthe same' odor can be produced by passingair through silica gel. 6 It is possible thatsubfilterable particles are associated withthis phenomenon.
Evidence for the association of particulate
1.14
105
o.
matter with outdc.or odors has sometimesbeen sought in the gross errors in odor in-tensities preducted on the basis of gas-phasedispersion of an odor source. However, theinterpretation of these experiments is opento doubt, and it is probable that the effectsare a result of fortuitous fluctuations in emis-sion. For example, Walter and Amberg havefound that concentrations of hydrogen sulfidein a kraft paper pulp mill recovery furnacecan vary from 100 ppm to as much as 1,000ppm. Such wide variations in emission mayhelp to explain the discrepancy, reported byWohlers 3 for a kraft mill, between the odorintensities observed and those predicted fromodor threshold concentrations and dilutionscalculated by Sutton's formula' The likeli-hood that errors in calculations of the atmos-pheric dispersal of true gases are compara-tively small is supported by experiments withgas tracers like sulfur hexafluoride (SF6).Collins et a/.19 and Turk et a/.11 have shownagreement between calculated and observedconcentrations of a tracer gas at distances upto about three miles from the emission pointto be within about 25 percent. It is true thatolfactory sensation is responsive to concen-trations that may be present for only briefintervals, whereas dispersion calculationsrefer to time averages for intervals of aboutone-half hour, and the tracer gas studies citedused 20-minute integrated samples. Some ofthe discrepancy between results of odor meas-urements on the one hand, and results fromcalculations or tracer gas tests on the other,may therefore be accounted for by the peak-to-mean ratios that result from the effects ofturbulence and eddies in the air stream.There are no published data on the minimumtime duration required for odor detection orodor nuisance responses. Efforts by Turk andcoworkers to determine the ratio of "instan-taneous" (one second) to average (20 min-ute) concentrations of tracer gas failed toshow significantly high values, possibly be-cause such occurrences are rare and escapedthe sampling grid,. In any event, the peak-to-mean ratios would have to be in the 1,000 to10,000-fold range to explain observed discrep-ancies, and we have no data that are based on
- meteorological factors alone to support suchextreme values.
C. HYPOTHETICAL MECHANISMS FORTHE ASSOCIATION OF ODOR WITH
PARTICLES
1. Volatile ParticlesLiquid or even solid aerosols may be suffi-
ciently volatile that their vaporization on en-tering the nasal cavity produces enough gas-eous material to be detected by smell. Suchaerosols may be relatively pure substances,such as particles of camphor, or they may bemixtures which release volatile components.The retention of the odorous properties ofvolatile aerosols will, of course, depend on theprevailing temperature and on the lengthof time they are dispersed in air. In a coldatmosphere, the relatively greater tempera-ture rise accompanying inhalation will accel-erate the production of gaseous odorant.
2. Desorption of Odorous Matter byParticles
Goetz 22 has treated the kinetics of the in-teraction between gas molecules and the sur-face of airborne particles. His theoreticalconsiderations were directed to the questionof transfer of toxicants by particles, but arealso applicable to odors. Even if a given aero-sol is intrinsically odorless, it could act as anodor intensifier if: 1. the sorptive capacity ofthe aerosol particles for the odorant weresmaller than the affinity of the odorant forthe nasal receptor and at the same time, 2.the sorptive capacity of the aerosol particleswere large enough to produce an accumula-tion of odorant on the particle surface. Suchaerosol particles would concentrate odorousmolecules on their surfaces, but the odorousmatter would be transferred to olfactoryreceptors when the aerosol entered the nasalcavity. The odorous matter would then bepresent at the receptor sites in concentrationshigher than in the absence of the aerosol. Theresulting effect would be synergistic. SeeChapter 10-C-3 for a discussion of syner-gistic effects of particles and irritants. Thesesynergistic effects may be analogous to par-ticle-odorant synergism. If an odorant ismore strongly adsorbed by the aerosol parti-cles than by the olfactory receptors, transferof the odorant to the receptors would be im-peded and the particles would actually at-tenuate the odor.
115
k:
3. Odorous ParticlesNo study has ever rigorously defined the
upper limit of particle size for airborne odor-ous matter. Particles up to about 8 or 10 X10-4 IL in diameter are considered to be mole-cules that can exist in equilibrium with asolid or liquid phase from which they escapeby vaporization. The vapor pressure de-creases :Is the molecular weight increases,and particles above about 10-s IL do not gener-ally exist in any significant concentration inequilibrium with a bulk phase; hence we donot consider them to be "vapors." Nonethe-less, it is possible that odorant properties donot disappear when particle sizes exceedthose of vapor molecules. Our knowledgeabout particles in the size range of 1 to 5 X10-aµ (up to about the size of small viruses)is relatively meager, and we do not knOwwhether or not they can be odorous, nor whatthe effect of an electrical charge on theirodorous properties might. be. Larger parti-cles may also be intrinsically odorous, al-though their more significant role may be tocontribute to odor by absorbing and desorb-ing odorous gases and vapors.
D. COMMON ODOR PROBLEMS.
Kerka and Kaiser ls surveyed State andlocal air pollution control personnel and com-piled the list of most frequently reportedodors shown in Table 8-1.
Of the 35 listings in Table 8-1, nine areeither known to be or suspected to be particu-late-borne. These nine include gisoline- anddiesel-engine exhaust, coffee roasting, restau-rant odors, paint spraying, roofing and streetpaving, asphalt manufacturing, home incin-erators and backyard trash fires, city inciner-ator burning garbage, and open-dump fires.
E. SUMMARY .
Airborne particulate matter, as an air pol-lutant category, is normally not consideredas a source of odor stimulation. However,there is evidence that some particulates hav-ing volatile components can produce an odorresponse in human receptors.
Further, by a suggested mechanism of ad-sorption and subsequent desorption, an odor-ant may be transferred by a particulate sub-
Table 8-1.MOST FREQUENTLY REPORTEDODORS
NumberSource of odor reported
Animal odors:Meat packing and rendering plants 12Fish oil odors from manufacturing
plants 5Poultry ranches and proce.cing 4
Odors from combustion processes:Gasoline and diesel engine exhaust 10Coke-oven and coalgas odors (steel
mills) 8Maladjusted heating systems 3
Odors from food processes:Coffee roasting 8Restaurant odors 4Bakeries 3
Paint and related industries:Manufacturing of paint, lacquer, and
varnish 8Paint spraying 4Commercial solvents 3
General chemical odorsHydrogen SulfideSulfur Dioxide 4Ammonia 3
General industrial odorsBurning rubber from smelting and
debonding 5Odors from dry-cleaning shops 5Fertilizer plants 4Asphalt odorsroofing and street
4Asphalt odorsmanufacturing 3Plastic manufacturing 3
Foundry odorsCore-oven odors 4Heat treating, oil quenching, and
pickling 3Smelting e- 2
Odors from combustible waste:Home incinerators and backyard
trash fires 4City incinerators burning garbage 3Open-dump fires 2
Refinery odors:Mercaptans 3Crude oil and gasoline odors 3Sulfur 1
Odors from decomposition of waste:Putrefaction and oxidationorganic
acids 3Organic nitrogen compoundsdecom-
position of protein 2Decomposition of lignite (plant cells) 1
Sewage odors:City sewers carrying industrial waste 3Sewage treatment plants 2
Probably related to meat processing plants.
107
strate. When one examines the various typesof odor sources which result in public aware-ness of an undesirable situation, a significantnumber of these listings are either known tobe or suspected to be particulate-borne. Asurvey of State and local air pollution controlofficials revealed that approximately one-fourth of the most frequently reported odorsare those which are known to be, or are sus-pected to be, associated with particulate airpollution. The sources of these odorous parti-cles are diverse, including diesel- and gaso-line-engine exhaust, coffee-roasting opera-tions, paint spraying, street paving, and theburning of trash. Despite the absence of anexact mechanism to explain the associationof odor with particulates, their intimate in-volvement in multiple categories of citizennuisance complaints cannot be ignored.
F. REFERENCES
1. Roderick, W. R. "Current Ideas on the ChemicalBasis of Olfaction." J. Chem. Educ., Vol. 43, pp.510-520, 1966.
2. Rossano, A. T. and Ott, R. R. "The RelationshipBetween Odor and Particulate Matter in. DieselExhaust." Preprint. (Presented at the AnnualMeeting of the Pacific Northwest InternationalSection, Air Pollution Control Association, Port-land, Oregon, November 5-6, 1964.)
3. Linnel, R. H. and Scott, W. E. "Diesel ExhaustComposition and Odor Studies." J. Air PollutionControl Assoc., Vol. 12, pp. 510-515, 1362.
108
17
4. Quebedeaux, W. A. "New Applications for Indus-trial Odor Control." Air Repair, Vol. 4, pp. 141-142, 170-171, 1954.
5. Turk, A. and Bownes, K. "Inadequate Stimula-tion of Olfaction." Science, Vol. 114, pp. 234-236,1951.
6. Turk, A., Kakis, F., and Morrow, J. "The Ad-sorbent Odor," Preprint. (Presented at the Amer-ican Chemical Society meeting, New York, Sept.1960.)
7. Walther, J. E. and Amberg, H. R. "ContinuousMonitoring of Kraft Mill Stack Gases with aProcess Gas Chromatograph." Tappi, Vol 50,pp. 19-23, 1967.
8. Wohlers, H. C. "Odor Intensity and Odor Travelfrom Industrial Sources." Intern. J. Air WaterPollution, Vol: 7, pp. 71-78, 1963.
9. Sutton, 0. G. "The Theoretical Distribution ofAirborne Pollution from ;.Factory Chimneys."Quart. J. Roy. Meteorol. Soc., Vol. 73, pp. 426-436, 1947.
10. Collins, G. F., Barlett, F. E., Turk, A., Edmonds,S. M. and Mark, H. "A Preliminary Evaluationof Gas Air Tracers." J. Air Pollution ControlAssoc., Vol. 15, pp. 109-112, 1965.
11. Turk, A., Edmonds, S. M., Mark H. L., and Col-lins, G. F. "Sulfur Hexafluoride as a Gas-AirTracer." Environ. Sci. Technol., Vol. 2, pp. 44-45, 1968.
12. Goetz, A. "On the Nature of the SynergisticAction of Aerosols." Intern. J. Air Water Pollu-tion, Vol. 4, pp. 168-184, 1961.
13. Kerka, W. F. and Kaiser, E. R. "An Evaluationof Environmental Odors." J. Air Pollution Con-trol Assoc., Vol. 7, pp. 297-301, 1958.
Chapter 9
THE RESPIRATORY SYSTEM: _DEPOSITION, RETENTION,AND CLEARANCE OF PARTICULATE MATTER
-118
Table of ContentsPogo
A. INTRODUCTION 111
B. ANATOMY OF THE HUMAN RESPIRATORY TRACT 111
C. FACTORS AFFECTING THE DEPOSITION AND RETENTION OFPARTICULATE MATTER IN THE RESPIRATORY SYSTEM 1121. Physical-Mathematical Treatments 112
a. Deposition Mechanisms 112b. Aerodynamic Factors 113c. The Models 114
2. Experimental Studies of Factors Affecting Depositim. suiRetention .... 116a. Total Deposition in the Respiratory Tract 117
(1) Effect of Particle Size 117(2) Physiological Parameters 117
b. Regional Deposition 118(1) Nasal Fractionation 118(2) Lung Deposition 118(3) Comparative Human and Animal Retention 119
3. Conclusions Reached about Alveolar Deposition 119
D. FACTORS AFFECTiNG THE CLEARANCE OF PARTICULATEMATTER FROM THE RESPIRATORY SYSTEM 1191. Clearance Model 1202. Clearance from the Tracheobronchial System 1213. Clearance from the Alveolar Surface 122
E. SUMMARY 123F. REFERENCES 123
List of FiguresFigure9-1 The Major Anatomical Features of the Human Respiratory System 1129-2 The Terminal Bronchial and Alveolar Structure of the Human Lung 1129-3 Calculated Fraction of Particles Deposited in the Respiratory Tract
as a Function of Particle Radius 1149-4 Fraction of Particles Deposited in the Three Respiratory Tract Com-
partments as a Function of Particle Diameter, 1159-5 Data from Figure 9-4 for the NasopharyngeAl Compartment Plotted
as a Log-probability Function (Minute Volume: 20 limin) 1169-6 Data from Figure 9-4 for the Pulmonary Compartment Plotted as a
Log-probability Function (Minute Volume: 20 limin) 1169-7 Schematic Portrayal of Dust Deposition Sites and Clearance Proc-
esses 120
List of TablesTable9-1 Respiratory Airflow Patterns for a Group of Healthy Young Men .... 113
: ;..110
r.
Chapter 9
THE RESPIRATORY SYSTEM: DEPOSITION, RETENTION, ANDCLEARANCE OF PARTICULATE MATTER
A. INTRODUCTION
In urban communities, exposure to atmos-pheric pollutants may constitute a healthhazard that is the most serious single conse-quence of air pollution. Chapters 10 and 11discuss the effects of particulate pollutantson health in terms of toxicological and epide-miological studies. Pollutants are likely toenter the human body mainly via the respira-tory system; other routes of entry_are ofminor importance. Damage to the respiratoryorgans may follow directly, or the pollutantmay be transported by some mechanism to aremote susceptible organ. It is apparent thata study of the effect on health of particulateatmospheric pollutants requires an under-standing of the mechanisms and efficienciesof deposition of particles in the respiratorysystem, and of the subsequent retention with-in, and clearance from. the system, as wellas its secondary relocation to other sites inthe body. This chapter provides a brief intro-duction-to the physics and physiology of de-position, retention, and clearance in the res-piratory system. More complete descriptionsmay be found in several reviews."
Experimental studies of the several fac-tors involved in deposition, retention, andclearance processes have been backed up bytheoretical treatments and, in the discussionwhich follows, descriptions of these theoreti-cal models precede those of experimentalwork. One of the latest theoretical models isthat developed by the Task Group on LungDynamics for Cominittee II of .the Interna-tional Radiological Pkotection Commission.*The Task Group's report establishes the use-fulness of the Stokes (mass median) diam-eter (cf. Chapter 1-A) of a particle as ameasure of deposition probability. This is of
practical importance, since the Stokes diam-eter may readily be determined under fieldconditions.
The anatomy of the respiratory systemplays an important part in determining theeffects of inhaled particles, and a very shortdescription of this anatomy is provided. Sev-eral extensive presentations of morphologicalstudies are.available,5. e and Davies' gives aformalized concept of the anatomy of thehuman respiratoiy tract.
B. ANATOMY OF THE HUMANRESPIRATORY. TRACT
The respiratory system is usefully brokendown into three main sections:
1. the nasopharyngeal structure;2. the tracheobronchial system; and3. the p ulmonary structure, within
which oxygen and carbon dioxide areexchanged between respired air andblood.
Figure 9-1 shows the location of these fea-tures. The nasal passages lead, via the naso-pharyngeal structure and the larnyx, to thetrachea and the bronchi, which are made upof 23 generations of dichotomous branchingtubes terminating in the alveolar (air) sacs.Figure 9-2 is a schematic representation ingreater detail, of the terminal bronchiole andpulmonary structure.
Estimates of numbers of alveoli differsomewhat from one experimenter to another:a recent suggestion 8 is that there are 300 mil-lion, together with 14 million alveolar duets.The alveoli are probably between 150 and4001& hi diameter, so that the total alveolarsurface varies between about 30 m2 and 80m2. The increasing total cross-sectional areawith progression down the respiratory tract
PHARYNX
RIGHTBRONCHUS
Al
1 BRONCHIOLESTERMINAL$ fq
L01,64 SA4 4.1\. LEFTP
BRONCHIOLES
.--t...vi A w ', 221 BRONCHUS
riga el' 4.),ttl.,
NASALCAVITY
ORALCAVITY
LARYNX
TRACHEA
RIGHT LUNG LEFT LUNG
FIGURE 9-1. The Major Anatomical Features of theHuman Respiratory System. (The diagram showsthe major divisions of the human respiritory tractinto nasopharyngeal, tracheobronchial, and pul-monary compartments.)
leads to a marked decrease in the velocity ofair movement with depth.
The nasopharyngeal and tracheobronchialstructures possess ciliated epithelium coveredwith mucus arising from goblet cells andsecretory glands. These structures also makeup the anatomical "dead space," since oxygenexchange between the blood and air does not.occur here. If the volunie of this dead spaceis Vd, the lungs must draw in a volume V inorder to obtain a volume VVd of fresh air,which is called the tidal volume. The surfaceof the pulmonary 'structure consists of non-ciliated moist epithelium that, although de-void of the secretory element found in thetracheobronchial tree, is covered by a sur-face-active material, without which alveoliwould totally collapse (atelectasis) at the endof respiration.
C. FACTORS AFFECTING THEDEPOSITION AND RETENTION OF
PARTICULATE MATTER IN THERESPIRATORY SYSTEM
1. Physical-Mathematical TreatmentsThe theoretical physical-mathematical
112
TERMINALBRONCHIOLE
RESPIRATORYBRONCHIOLE
ALVEOLI
FIGURE 9-2. The Terminal Bronchial and AlveolarStructure of the Human Lung. (The diagramshows the pulmonary structure of the respiratorytract.)
treatments use information on the anatomicalstructure and airflow rates in the respiratorytract, together with knowledge of the physi-cal factors influencing the deposition of par-ticles. The deposition mechanisms will beconsidered first; aerodynamic factors con-nected with airflow and gas mixing in therespiratory system will then be mentionedbefore proceeding to a discussion of the threemain models which have been developed.
a. Deposition Mechanisms
Three mechanism are of importance in thedeposition of particulate matter in the respi-ratory tractinertial impaction, gravitation:al settling (sedimentation), and diffusion(Brownian motion) . The relative significanceof these deposition mechanisms varies withanatomical and physiological factors, with,the nature of the airflow, and with the char-acteristics of the aerosol such as particleshape and density.
Particles in an airstream impinge onto a
121
surface when the inertia of the particle isgreat enough to overcome the resistive forcesof the medium and intercept the surface ofthe obstacle. If gravity is neglected, the pathof the particle is determined by the air veloci-ty, the mass and air resistance of the par-ticle, and size and shape of the obstacle. In-ertial impaction is therefore of greatest im-portance in the deposition of large particlesof high density, and at points in the respira-tory system where the direction of flowchanges at branching points in the airways.
The size of the particle as well as its densi-ty are singificant factors in determining theimportance of deposition by gravitational set-tling. The terminal velocities (settling veloci-ties) of spheres of unit density in air for10-A, 1-p., and 0.1-s particles are 2.9 x 10-3cm/sec, 3.5 x 10-3 cm/sec, and 8.6 x 10-3 cm/sec respectively. Density also plays a partsince the sedmimentation behavior of a 0.5-A particle of density 10 g/cm3 would beequivalent to that of a unit density particle of1.5-s diameter. Hence, gravitational settlingis most important in the depositon of largeparticles or of high-density particles such asdusts of heavy metals. Irregularly shapedparticles will have an aerodynamic size lessthan the size predicted on the basis. of themeasured geometric diameter.
The third main mechanism active in bring-ing about deposition of particles in the res-piratory tract is Brownian movement or dif-fusion; it is the result of bombardment of thoparticles by air molecules which are in rapid,random, thermal motion. Diffusion is negli-gible for large particles (say above 0.5-Adiameter), while it may be the major mecha-nism for the deposition of small particles(below 0.1,u) in the lower pulmonary tract,where airflow rates are lower and the dis-tances to the walls are less.b. Aerodynamic Factors
Two aerodynamic factors, namely, flowrates and gas mixing, are incorporated inthe models of the respiratory system.
During the respiratory cycle, the actualairflow rate varies from zero up to a maxi-mum value and then back down to zero. Usu-ally the expiratory phase is longer than theinspiratory phase and there may be pauses
S
between the two phases. A study of the res-piratory airflow patterns of healthy youngmen at rest and under a wide range of workloads Was made by Silverman et al. The max-imum inspiratory flow rate increased from amean value of 40 1/min in sedentary subjectsto 100 1/min at an exercise level of 622 kg-m/min and to 286 1/min at an exercise levelof 1660 kg-m/min. The corresponding valuesfor maximum expiratory flow rates were 32,107, and 322 1/min. The collected results areshown in Table 9-1.
Changes in flow rate resulting from physi-cal activity have a profound effect on particledeposition in the respiratory system; this ef-fect in turn depends upon the aerodynamicsize of the particulate material inhaled. It hasbeen demonstrated by:./Amdur, Silverman,and Drinker " that the inhalation of irritantparticulate material, such as sulfuric acidmist, can decrease the maximum inspiratoryand expiratory flow rate in human subjects.Such alterations produced by irritant par-
Table 9-I. -RESPIRATORY AIRFLOW PATTERNSFOR A GROUP OF HEALTHY YOUNG MEN."
Exercise Inspiratoiy flow Expiratory flowlevel rate 1/min (max) rate 1/min (max)
Sedentary 40 32622 kg-m/min 100 1071660 kg-m/min 286 322
tides could also affect deposition patterns ofparticulate matter in general, and may re-present the physiological defense response ofthe body. .
Another factor to be considered in the dep-osition of particulate matter in the lung isthe role of mixing of intrapulmonary gasflow. A study of this factor has been madeby Altshuler and co-workers " using 0.4-spartides suspended in air. From the meas-ured wash-in and wash-out rates (after re-turn to particle-free air) , the authors wereable to calculate the volume of new air whichmixed with the residual air. Their datashowed that at a tidal volume of 500 ml, notmore than 11 percent to 27 percent of new airin each successive breath actually mixed withthe residual air. It follows that nondiffusible
113
122
particles (above 0.5 p) will tend to penetrateonly to the depth of the new air, while smallerparticles will have great enough diffusionvelocities to move independently into thestatic: air in the lung, in the same way thatgas molecules do.c. The Models
For the present purposes, the most impor-tant model is that of the Task Group on Lung'Dynamics! However, two earlier studies,those of Findeisen '= and Landahl," are ofsignificance, since they were both consideredas a basis for the Task Group model. TheTask Group finally selected Findeisen's ana-tomical model, since it appeared that therather more sophisticated treatment ofLandahl gave no better estimates of deposi-tion values. Further, the cumulative volumedown to the end of the terminal bronchioles 'in the Findeisen model is more in keepingwith the anatomical dead space as determinedby physiological measurements.
Findeisen '= predicted the percentage ofdeposition and the site of deposition of particles of various zizes in the respiratory tract.He estimated there would be a critical parti-cle size of about 0.3-1L to 0.4-s radius forwhich a minimal amount of 34 percent wouldbe deposited. This deposition would occurpredominantly in the terminal airways andalveoli, thus suggesting that particles of thissize should not be dismissed as toxicologicallyunimportant. Findeisen also estimated thatthe percentage deposition of 0.3-s radius par-ticles would be 68 percent as much as that of1--A radius. particles. His calculated deposi-tions are shown in Figure 9-3. Experimentalwork on deposition of particles smaller than1--A diameter have borne out Findeisen's pre-dictions.
Findeisen's concepts of the anatomy of thepulmonary tract have been criticized byWeibel. Findeisen assumed equal and con-stant flow rates for inspiration and expira-tion; a situation which does not prevail dur-ing the respiratory cycle. Furthermore, thissimple respiratory pattern does not take intoaccount the unique distribution of air in thelungs, or the factors of intrapulmonary mix-ing of tidal and residual air in the lungs.
Landahl 15 made a similar theoretical study
114
0
us DEPOSITION IN RESPIRATORY
00.0.
20.0goasU.
0.2
SYSTEM
0.1
C..10'2 10
RADIUS,
DEPOSITION IN ALVEOLARREGION ONLY
FIGURE 9-3. Calculated Fraction of Particles De-posited in the Respiratory Tract as a Functionof Particle Radius." (The figure represents. thecalculated efficiencies of deposition of particles ofvarious sizes, in the tracheobronchiat and alveolarregions of the respiratory system, and shows thesize for minimum efficiency.)
of the problem of particle deposition in therespiratory tract, but included the mouth andpharynx in his anatomical model. He em-ployed several tidal volumes and breathingfrequencies in his calculations, but in all casesassumed a constant flow for both the inspira-tory and expiratory phases. The calculationsyielded deposition values for both phases, andtook into account the progressively smallerfraction of each tidal volume which pene-trated to the various depths. Deposition invarious regions for spheres of unit density inthe size range 20 A to 0.2 A was predicted tofall to a minimum at the size where the pre-dominant force bringing about deposition isshifting from gravitational settling to dif-fusion. An increase was found in retentionwith larger tidal volumes.
Landahl 15 also made a separate considera-tion of deposition in the nasal passages. Ear-lier studies did not take into account impac-tion of particles on nasal hairs, or depositionby inertial forces as the airflow changes di-rection, or sedimentation within the nasalchamber. Assuming a flow rate of 18 1/min,about 75 percent of 10-14 particles would beretained in the nose. Corresponding valueswould be about 50 percent fore.5;-/L particles
123
and 10 percent for 1-IL particles. Landahlcalculated that at flow rates greater than 181/min, essentially 100 percent of the particlesabove 10 IL would be retained in the nose andthat there also would be substantial retentionof 2-1& to 5-IL particles. Nasal deposition isnegligible for particles below 1 IL in diameter.It follows that the estimated pulmonary dep-osition values of Findeisen would have to berevised downward for the large particles.
The Task Group on Lung Dynamics usedthe conventional division of the respiratorytract into three compartments, and madethree fundamental assumptions in the de-velopment of their model. These were:
1. The log-normal (Chapter 1-B) fre-quency distribution is generally ap-plicable to particle sizes in the atmos-phere. It should be noted that this as-sumption is by no means universallyaccepted.
2. The physical activity of the individualaffects deposition primarily by its ac-tion on ventilation, since physiologicaladjuitment to the demands of in-creased minute ventilation is to in-crease tidal volume more than respi-ratory frequency. In terms of produc-ing the greatest change in depositionthroughout the respiratory tract, theeffect of an increase in volume at aconstant respiratory frequency wasconsidered. (A frequency of 15breaths per minute was used togetherwith tidal volumes of 750, 1450, and2150 'cm3 (BTPS) ; the lowest tidalvolume is considered representativeof a mild-to-moderate activity state.)
3. The aerodynamic properties of theparticle, the physiology of respira-tion, and the anatomy of the respira-tory tract provide a basis for a mean-ingful and reliable deposition model.
The Task Group's aim was to amalgamatesize-deposition relationships into a general-ized form which would directly permit theprophetic use of dust-sampling information.By conventional sampling methods, the countmedian diameter or the mass median diam-eter is Obtainable along with the geometricstandard deviation, ag (Chapter 1-A). The
measurement of one diameter permits thecalculatidn of the other, and both can be ex-pressed as aerodynamic (Stokes) equivalentdiameters. The Task Group used calcula-tions basically similar to those of Findeisento estimate the deposition in the three res-piratory compartments. When the mass me-dian aerodynamic diameters of 0.01 IL to 100 ILof various distributions, as represented bydifferent geometric standard deviations, wereplotted against the estimated mass deposi-tion of particles occurring in each respira-tory compartment, surprisingly little vari-ability was seen with 0g ranging from 1.2to 4.5. The results of these calculations areshown in Figure 9-4; the curves indicate arelationship between the mass median aero-dynamic diameter and the gravimetric frac-tion of the inhaled particles which would bedeposited in each anatomical compartment.Within these limits (0.01 IL to 100 K), themass median aerodynamic diameter served
110.2 101 10° 101
MASS MEDIAN DIAMETER, 1,1
FIGURE 9-4. Fraction of Particles Deposited in theThree Respiratory Tract Compartnients as a Func-tion of Particle Diameter.' (This figure shows the
. deposition efficiencies calculated by the Task Groupon Lung Dynamics.)
102
to characterize the deposition probabilities ofthe entire particle size distribution fromwhich it emerged. Other parametric' func-tions of the particle distribution failed toproduce such simple cohesive relationships.
The effect of the varying tidal volumes isshown in the original report (Figure 12, Ref-erence 4), but it is possible, for practical pur-poses, to use a mean curve for 1450 ml torepresent all three respiration states. Thisimplies that the minute volume will controlthe total amount of particulate material de-posited but will not ordinarily have mucheffect on the percentage deposition.
The final step was to plot the combinationof mean distribution versus mean respira-tory performance curves on log-probabilitypaper, a manipulation suggested by the sig-mold shape of the nasopharyngeal and pul-monary deposition curves. The results areshown in Figure 9-5 and Figure 9-6. Thedeposition in the tracheobronchial compart-ment is considered, for practical purposes,
1 10 30 50 70 90DEPOSITION, %
99 99.9
FIGURE 9-5. Data from Figure 9-4 for the Naso-pharyngeal Compartment Plotted as a Log-proba-bility Function. (Minute volume: 20 1 /min)..(The figure shows that there is a roughly linearrelationship between deposition efficiency and thelogarithm of the particle size.)
116
as constant at approximately 8 percent ofthe inspired particulate matter.
The results of the Task Force's calcula-tions suggest the type of atmospheric sam-pling data that will be most meaningful inthe correlation of atmospheric particle con-centrations and human health. In particular,the insensitivity of the model to aerodynamicsize distribution leads the Task Force to pro-pose the concept of "respirable" dust sam-ples, in which the samplersare designed andcalibrated to provide data from which onecan determine the mass median diameter inaerodynamic terms. Such considerationshave a special significance in connection withparticles, such as asbestos, which possess anabnormal deposition behavior.
2. Experimental Studies of FactorsAffecting Deposition and Retention
Experimental studies of the deposition ofinhaled particulate material may be dividedinto two broad categories. The first group
102
101
10-1
10.21
1 I I I I I I I
301 1 5iZ1
j90
DEPOSITION, 96'.
99 99.9
FIGURE 9-6. Data from Figure 9-4 for the Pulmo-nary Compartment Plotted as a Log-probabilityFunction' (Minute Volume: 20 1/min). (This fig-ure shows that there is a roughly inverse linearrelationship between deposition efficiency and thelogarithm of particle size.)
rwa
deals with the measurement of total deposi-tion in the respiratory tract, and the secondgroup is concerned with regional depositionwithin the various areas of the respiratorytract.a. Total Deposition in the Respiratory Tract
Experimental studies of deposition werefirst made by Lehmann et al.," Saito,"Owens," Baumberger,19 and Sayers et al."Drinker et al.," measured respiratory deposi-tion in man with simultaneous recording ofrespiratory frequency and minute volume.The concentration of particulate matter wasmeasured in the chamber, from which airwas inhaled, and in the exhaled air. An aver-age retention value of 55 percent at a fre-quency cf six to 18 respirations per minutewas found.
(1) Effect of Particle Size.The first sys-tematic study of the influence of particle sizeon the percentage deposition of inhaled dustwas made in 1940 by Van Wijk and Patter-son." The subjects. at rest, inspired min-eral dust particles from the air of South Af-rican gold mines. Percentage deposition ap-proached 100 percent above 5 p and had de-creased to about 25 percent at 0.25 p, to thelimit of the measuring technique.
Brown 21.24 made a series of tests on hu-man subjects in which he found that the per-centage deposition is directly proportionalto the particle size and to the density of thesuspended material. (Size refers here to thephysical dimensions of aggregates of par-ticles rather than to unitary particles.)
More sophisticated experiments by Alt-shuler et at." have used a homogeneous aero-sol of triphenyl phosphate, with particlesizes in the range 0.14 p. to 3.2 p to studydeposition in human subjects. It was foundthat deposition was dependent on particlesize and that the minima deposition diam-eter was 0.4 A, which is in reasonable accordwith the prediction made by Findeisen (0.6It to 0.8 p) 20 years earlier.
The deposition of coal dust in human sub-jects has been shown 26 to rise from a mini-mum efficiency of about 30 percent at 0.5to almost 60 percent at 0.1 p (mass mediandiameter). Such an overall efficiency sug-gests that the absolute efficiency of deposi-tion of the particles smaller than 0.1 p in
the pulmonary air spaces is close to 100 per-cent. Direct measuremmt of the particulatematter concentration in samples of alveolarair showed an efficiency of removal of essen-tially 100 percent down to about 0.5 p andbetter than 80 percent for particles well be-low 0.1 p."
A hygroscopic particle may collect suffi-cient water to increase its size significantlyover that in the dry state. Dautrebande andWalkenhorst 26 have therefore compared thedeposition of sodium chloride with that ofcoal dust. Using the dry size of the salt par-ticles, deposition curves different from thosefor coal dust were obtained, but on correcting(by a factor of seven) to account for thegrowth of salt to liquid droplets in the res-piratory tract, the curves were quite similarfor the two particles. This result is of con-siderable practical significance, as it meansthat hygroscopic particulate air pollutantswill be deposited to a higher degree thanmineral particles of an equal size. .The TaskForce Report4 gives equations which maybe applied to correct for the effect of hygro-scopicity on deposition.
(2) Physiological parameters.In Brown'sexperiments,". 24 the effect of varying res-piratory frequency, tidal volume, and minutevolume was determined by making measure-ments on subjects breathing at rest, undervarious work loads on a bicycle ergometer,and breathing air containing added CO:. Theconclusions of this work were:
1. Percentage deposition is inverselyproportional to respiratory rate forrates below 20 per minute and anincrease in frequency above 30 perminute causes no further change inpercentage deposition;
2. Percentage deposition is inverselyproportional to the minute volume;and
3. Percentage deposition is unaffectedby tidal volume, vital capacity, orrelative humidity of the inspired air.
The results are essentially in agreementwith the predictions of Findeisen and Lan-dahl (although no effect of tidal volume ondeposition was observed).
In general agreement with Brown's result
for respiratory rate, Altshuler et al.25 foundin their experiments that slower, deeperbreathing gave greater deposition thanfaster, shallow breathing. It is also shownthat, in agreement with prediction, the dif-ferences due to respiratory frequency aregreater for 1.6-ft particles than for 0.14-pparticles. For the 1.6-k& particles, impactionand settling are the dominant mechanisms
"Thdeposition, and the number settling variesas ihe first power of time. With the 0.14-p,partilis, Brownian motion is the dominantdeposition mechanism, and the number set-tling varies as the square root of time.
Experiments with stearic acid particles 28have revealed an interesting phenomenon ofminimal deposition at normal breathing fre-quencies of 15 to 20 breaths per minute andan increase when the frequencies were eitherhigher or lower than this. A range of res-piratory rates from less than 5 Mier minuteto more than 35 per minute was used, andparticle diameters lay between 1 p and 5 p.On the other hand, Morrow and Gibb 29 findthat the deposition of 0.04-ft sodium chlorideparticles in dogs and human subjects de-creases with an increase in breathing fre-quency. The deposition percentages them-selves (66.5 percent in dogs, 63.4 percent inman) are close to those predicted by Fin-deisen. An increase in tidal volume increasedthe deposition in these experiments in dis-tinction to the absence of a tidal volume ef-fect found by Brown.
There appears to be a direct relationshipbetween percentage deposition and holdingtime in the lungs for particles of 0.55 IA di-ameter."b. Regional Deposition
The experimental study of regional depo-sition of particles is more complex than isthe determination of overall total depositionin the respiratory tract. Various specializedtechniques such as the inhalation of radio-active particles followed by external count-ing over specified portions of the chest, orradioautography of the lungs, have been em-ployed. The technique of fractionating ex-haled air and counting the particles in eachfraction has also been used.
(1) Nasal Fractionation. Lehmann,"
118
using a test dust of unspecified size, founda median nasal deposition of 46 percent in185 normal subjects and 27 percent in 241silicotics. Dust-laden air was blown throughthe nose and out through a tube in the mouth.Tourangeau and Drinker 32 Wind depositionefficiencies of 10 percent to 25 percent withairflow rates through the nose of 4 to 12liters per minute. Their dust was calciumcarbonate of a size comparable to the silicaparticles found in silicotic lungs. Reversalof the direction of flow did not alter thevalues.
The most extensive experimental studiesof nasal penetration have been made by Lan-dahl's group.". 34 The results, especially forcorn oil particles, confirm theoretical predic-tions," and nasal deposition is found experi-mentally to have a strong dependence on air-flow rate.
(2) Lung Deposition.Wilson and LaMer 26 used an aerosol of glycerol containingNa24C1 as a tracer in seven normal subjectswho breathed through the mouth at varyingfrequencies. Particle sizes were in the rangeof 0.2. IA to 2.5 II. External chest counts en-abled estimates of lung burden to. be made,and the pulmonary deposition curve showeda maximum of about 80 percent for particlesof about 1.6-p diameter. A second peak at0.4 k& was interpreted in terms' of the differ-ing optimum sizes for deposition in the finestairways and in the pulmonary air spaces;deposition in these two areas was not dis-tinguished by the method employed.
Indirect estimates of upper respiratory,alveolar, and total deposition in human sub-jects were made by Brown et at," using atechnique for fractionating the exhaled air.In each successive portion, the CO2 contentwas measured together with the particlecount and thus the amount of lung air ineach portion of the sample could be esti-mated. Equal removal efficiencies in bothdirections were assumed, and a series of ex-pressions was developed for calculating total,alveolar, and upper respiratory deposition.The median particle size of the china claytest dust ranged from 0.24 It to above 5 14and the total retention decreased systemati-cally from 90 percent or more for particles5 p and greater, down to 25 percent to 30
percent for 0.25-p particles. Tracheobron-chial retention also decreased systematicallywith particle size but reached zero at a finitesize above 1 p. Alveolar retention, calculatedas the percentage of the number of particlesreaching the alveoli, remained between 90percent and 100 percent for all sizes down toabout 1 p.; below that, it decreased in pro-portion to total retention. The calculatedcurve for alveolar deposition showed an opti-mum size at 1 p.
(3) Comparative Human and Animal Re-tention.A technique essentially similar tothat used by Brown in his experiments onhuman subjects (see Section C- 2 -a -(2)above) has been employed by Palm, McNer-ney, and Hatch'? for studies on guinea pigsand monkeys. This provides a valuablechance to compare results of experiments onlaboratory animals and man. The test dustsincluded china clay, carbon, antimony tri-oxide, and bacillus subtilis var. niger. Theoverall pattern of the results was similar inthe experimental animals and in man. Theactual deposition and retention values werevery close for the monkey and for man. Forthe guinea pig, total retention was close to100 percent for 3-p. particles and fell sys-tematically with decreasing particle size. Incomparison with ma,n, the total retentionwas higher, especially in the lower size range.Alveolar retention was essentially the samein both species, and it is the tracheobron-chial retention which higher in the guineapig than in man. Although alveolar deposi-tion in the guinea pig was much lower for1.5-a particles than in man, because of theremoval of these particles in the tracheo-bronchial tract, the optimum size for alveolardeposition was similar in both species.
.3. Conclusions Reached about AlveolarDeposition
Three important conclusions may bereenlied about the effect of particle size onalveolar deposition:
1. There is a maximum efficiency ofdeposition at a size between about 1and 2 p;
2. There is minimum efficiency for asize of.around 0.5 p; and
3. The percentage of particle depositionfor sizes less than 0.1 p is just asgreat as for sizes more than 1 p, (Fig-ure 9-3). This last conclusion is notalways given enough weight, eventhough its prediction by Findtsen "has been adequately confirmed ex-perimentally.20. 29
On the other hand, the importance of thesecond conclusion above should not be over-emphasized, as it refers only to the proba-bility of deposition. If their number, andtherefore the mass deposited, is relativelygreat (as may well be for aged aerosols),then particles in the 0.1-p. to 0.5-µ size re-gion may be as important as smaller andlarger particles in provoking toxic response.This is also important when considering par-ticles containing absorbed material.
D. FACTORS AFFECTING THECLEARANCE OF PARTICULATE
MATTER FROM THE RESPIRATORYSYSTEM
A well-known response of a living orga-nism to foreign matter is its attempt to riditself of, or in some way inactivate, the un-wanted material. The overall effectivenessof clearance mechanisms in the lung is wellillustrated by the finding that the actualamount of mineral dust found in the lungsof miners or city dwellers at autopsy is onlya minor fraction of the total dust that musthave been deposited there during their lives.The clearance of certain particles may bevery slow. The rate is dependent upon size,site of deposition, and chemical constitution.
Relative to other factors, the importanceof removal from the respiratory system oftrapped particulate materials depends on therate at which the material elicits a patho-logical or physiological response. The effectof an irritant substance which produces arapid response may depend more on theamount of initial trapping than on the rateof clearance. On the other hand, materialssuch as carcinogens, which may produce aharmful effect only after long periods of ex-posure, may exhibit activity only if the rela-tive rates of clearance and deposition aresuch that a sufficient concentration of mate-rial remains in the body long enough to cause
12& 119
la)
BLOOD
(I)
,(c)
el
1
NASOPHARYNGEALCOMPARTMENT
(b)
04
TRACHEOBRONCHIALCOMPARTMENT
/ D5
`milimmul PULMONARYCOMPARTMENT
(hl
LYMPH
GASTRO-INTESTINAL
TRACT
FIGURE 9-7. Schematic Portrayal of Dust Deposition Sites and Clearance Processes. (This diagram illus-trates the various deposition sites and clearance mechanisms used in the model of the lung developedby the Task Group on Lung Dynamics, and described in the text.)
pathological change. In such a case, theamount of initial' deposition will be of rela-tively minor importance.
Different clearance mechanisms operate inthe different portions of the respiratory tract,so that the rate of clearance of a particlewill depend not only on its physical andchemical properties such as shape and size,but also on the site of initial deposition. Fur-thermore, the presence of a nonparticulateirritant or the coexistence of a disease statein the lungs may interfere with the efficiencyof clearance mechanisms and thus prolongthe residence time of particulate material ina given area of the respiratory tract. Kotinand Falk 38 have emphasized the possible im-portance of this, interaction in the patho-genesis of lung cancer (Chapter 10).
1. Clearance ModelThe Task Group on Lung Dynamics con-
sidered the respiratory clearance of particu-
late matter, as well as its deposition, and themodel they developed provides a convenientstarting point for a discussion of experimen-tal work on clearance.
Figure 9-7 presents a schematic diagramof all deposition sites and clearance proc-esses. The three conventional compartmentsof the respiratory tract discussed in connec-tion with the deposition model are used here.DI is the particulate material inhaled; D2is the material in the exhaled air; D3, D4, andD5 are the particles deposited in the naso-pharyngeal, tracheabronchial, and pulmonatycompartments respectively, expressed as per-centages of DI and _determinable from thedeposition model. In addition to the respira-tory tract, three other compartments arelisted: The gastrointestinal tract, systemicblood, and the.lymph. The different absorp-tion and translocation processes which areassociated with the clearance of various com-partments are as follows:
714Wi..`
a. Rapid uptake of material depositedin the nasopharynx directly into thebloodstream. ,
b. Rapid clearance of all particulatematter from the nasopharynx by cil-iary transport of mucus. This route,and d, have clearance half-times ofminutes.
c. Rapid absorption of particles de-posited in the tracheobronchial com-partment into the systemic circula-tion.
d. The rapid ciliary clearance of thetracheobronchial compartment. Par-ticles cleared by this route go quan-titatively to the gastrointestinal tract.
e. The direct translocation of materialfrom the pulmonary region to the
f. The realtively rapid clearance phaseof the pulmonary region dependenton recruitable macrophages. This inturn is coupled to the ciliary mucustransport process for which a half-time of 24 hours has been suggested.
g. A second pulmonary clearance proc-ess, much slower than f, but still de-pendent upon endocytosis and ciliarymucus transport. This process israte-limited in the pulmonary regionby the nature of the particles per se.
h. The slow removal of particles fromthe pulmonary compartment via thelymphatic system.
i. A secondary pathway in which par-ticles cleared by pathway h are intro-duced into the systemic blood.
j. The collective absorption of clearedmaterial from the gastrointestinaltract into the blood. No attempt ismade to include this factor in the de-velopment of the model.
The use of the model requires a knowledgeof values for two parameters for each of thepathways just described. These are theamount of material. residing in,the compart-ment which follows a particular exit path(regional fraction), and the rate at whichthat fraction of the material is cleared (bio-logical half-time). In some cases the kinetic
values are physiologically controlled and aremore or less independent vf the nature ofthe particulate material. In other cases thephysiochemical nature of the deposited mate-rial is the critical factor.
A classification of inorganic compounds isgiven in the Task Force Group Report, whichcontains the best available information orboth deposition and clearance of inhaledparticles.
The Task Force Group stressed the needfor research in the area of solubilities ofvarious compounds in water, in very dilutealkali, and in the presence of proteins. Someof the work done by Morrow et al." corre-lates clearance of material from the lungswith other properties such as ultrafilterabil-ity and clearance from intramuscular injec-tion sites. These data will be of value inunderstanding the effect of physiochemicalproperties on clearance.
It will be seen that the clearance mecha-nisms can be divided broadly into those de-pending on ciliary action and those whichoperate in the virtually nonciliated pulmo-nary region. The two sections which followdescribe experimental work concerned withtheie two general subdivisions.
2. Clearance from the TracheobronchialSystem
A blanket of mucus in the tracheobron-chial region is kept in continual upwardmovement by the ciliary activity of the col-umnar epithelium lining which extends downas far as the terminal bronchioles. The fre-quency of the ciliary beat has been found 4o 41to be 1,300 per minute in the rat, while theoverlying mucous fluid was found to moveat an average rate of 13.5 mm per minute.Similar transport rates of 15 mm per min-ute in excised trachea, and 18 mm per min-ute in intact animals, have been reported byAntweiler.42 In this latter study, several par-ticulate materials were used, including soot,coal dust, lycopodium spores, cork dust, alu-minum powder, and ,glass and lead spheres.Transport rates seemed to be unaffected bysized weight, or shape of the particles exceptin the case of the glass spheres, which weresaid to be sufficiently smooth to &flow the
'LOU.121
mucus to flow over them rather than to trans-port them.
It has been demonstrated 43.44 that in thehuman lung the mucus flows over only 10percent to 20 percent of the theoreticallyavailable surface at the dividing passageswhere the airways branch. The mucousblanket divides and flows in two directionsaround the margins of the opening. Thisphenomenon, taken together with the greaterprobability of impact deposition at bifurcations, may explain why histological sectionsshow accumulations of particles at bronchialbranch points.49
In studies of respiratory system clearance,use has been made of mono-disperse aerosolstagged with radioactive substances to per-mit the subsequent fate of the material tobe followed by external counting techniques.In general, the results indicate that clear-ance occurs in two distinct phases of abouttwo and ten hours duration, probably repre-senting the clearance of particles from theproximal and distal 'Parts of the bronchialtree. Albert et al." studied clearance fromthe human lung of 3-p and 5-µ iron oxideparticles tagged with 51Cr and 198Au. Therapid phase of clearance was completed with-in one day, and in most cases within 12hours. The clearance curves obtained inthese studies did not differ substantiallyfrom those obtained earlier by Albert andArnett 47 who used a heterogeneous iron ox-ide aerosol, suggesting that. the actual dis-tribution function of particle sizes may beof little importance in determining clearancerates. However. Holma 49 generated a "bi-disperse" aerosol of 6-p and .3-p polystyreneparticles, tagged respectively with 399Au and48sc, and measured simultaneous clearanceof the two sizes in rabbits. The larger par-ticles cleared more rapidly than the smallerones. The mean half-life for the initial phasewas 0.48 hours for the 6-p particles and 1.07hours for the 3-p particles: The respectivehalf-lives for the long clearance phase were69.7 hours and 210 hours.
The effect of irritant gases on clearance ofpartieles is obviously of significance whereair pollution involvev.this combination offactors. :t*
Dalhamn's 40° 41 studies showed that the
122
acute response to irritant gases such as am-monia, formaldehyde, or sulfur dioxide wasa cessation of ciliary beat. The time to ces-sation was dose-related. Chronic exposureof rats to one of the irritants (sulfur dioxide)slowed down or caused a complete cessationof the transport of tracheal mucus, but theaverage beat frequency of the cilia was thesame as in normal animals. The cessationof clearance was a result of an increase in thethickness of the mucous layer of from 5 A
to 25 A.The material carried upward by ciliary
action is swallowed and thui enters the gas-trointestinal tract. Brieger and LaBelle 49exposed animals to a water-insoluble dye anddemonstrated that 24 hours after the termi-nation of exposure, over 50 percent of thetotal dye found in the body was in the in-testinal tract. This phase could persist forseveral days, during which time a significantintestinal burden was present. The concen-tration of dye finally fell to very low valuesafter a week or so, and most of the dye thatremained in the body was found in the lung,indicating that the rapid phase of ciliaryclearance was finished. It has also beenshown 50 that uranium dioxide, cleared fromthe respiratory system to the gastrointestinaltract by ciliary action, is responsible for thehigh urinary uranium levels seen during thefirst days after exposure to uranium dioxidedust. The possibility of consequences of rela-tively high concentrations of an atmosphericpollutant appearing in organs remote fromthe lungs must not be overlooked. In thisconnection, the high incidence of stomachcancer in areas suffering from high levelsof atmospheric pollution takes on a particu-larly ominous appearance.
3. Clearance from the Alveolar SurfaceParticles) deposited on the alveolar sur-
face may be removed by any of the mecha-nisms (e) to (i) given in the clearance modelof Section D-1, and they may also becomesequestered by a tissue reaction within thelung (pneumoconiosis), or become bound toprotein material in the lungs. Of the sev-eral clearance mechanisms, the most rapid isthat involving recruitable macrophages(phagocytic cells contained on the alveolar
surface epithelium). Phagocytosis may alsoserve to render the particles incapable of in-juring or irritating the alveolar surface epi-thelium and may to some extent prevent thepenetration of the particles into the inter-stitium of the lung. The origin and behaviorof these alveolar macrophages have beenthe subjects of active research in recentyears.45. 51-53
LaBelle 54. 58 demonstrated that the clear-ance of particulate matter by phagocytosiscan be markedly influenced by the dust loadpresented to the lung. The initial observa-tion was made that clearance curves obtainedwith microgram quantities of activated ura-nium dioxide were noticeably different fromthose obtained earlier using milligramamounts. When carbon particles were addedto the activated uranium dioxide to bringthe total weight of administered dust intothe range of the earlier studies, the clearancecurves were quite similar. In seeking thereason for this finding. LaBelle demon-strated that the number of free phagocyteswashed out of the lungs was related to thedust load and that the amount of dust elimi-nated from the lungs during the early post-exposure period was proportional to the num-ber of free phagocytic cells present. Withinthe limits of experimental error, the kineticsof elimination of particles and the kineticsof the disappearance of the phagocytic cellsfollowing exposure were identical for bothinhalation and intratracheal exposures.
The relationship between concentrations inthe different respiratory regions during al-veolar clearance has been the subject of ashort-term study by Gross, Pfitzer, andHatch.56 The clearance of four kinds of dustburdens (antimony trioxide, ferric oxide,quartz, and coesite) was followed in ratswhose lungs had been loaded using the in-halation and intratracheal injection tech-niqnes. Initially, although the greater con-centration of dust was to be found in theproximal alveoli, dust deposition was alsoprominent in alveoli distal to alveolar ducts.However, within .3 or 4 days, the dust in thedistally situated alveoli had largely disap-,peared and had apparently become concen-trated in the proximal alveoli. This stagna-tion of dust in the evaginating alveoli of the
respiratory bronchioles and alveolar ductsmay help to explain the greater vulnerabilityof these regions to inhaled irritants.
E. SUMMARY
The respiratory system may be dividedinto three sectionsnasopharyngeal, tra-cheobronchial, and pulmonary systems. Dep-osition and clearance mechanisms may differfor the various parts of the respiratory tract.A particle of any size which passes the naso-pharyngeal region may be deposited in theremainder of the respiratory tract and, al-though the actual mechanism of depositionis primarily dependent upon the particle size,the shape of the particle can also affect theefficiency of its deposition. Consequently, ifatmospheric dust loads are to be relatedquantitatively to health hazards, the dustsamplers used for monitoring should havecollection characteristics similar or the sameas the human lung. The fast phases of thelung clearance mechanisms are different inciliated and nonciliated regions. In ciPatedregions, a flow of mucus transports the par-ticles to the entrance of the gastrointestinaltract, while in the nonciliated pulmonary re-gion phagocytosis by macrophages can trans-fer particles to the ciliated region. The rateof clearance is an important factor in de-termining toxic responses, especially forslow-acting toxicants such as carcinogens.In addition, since the clearance of particlesfrom the 'respiratory system primarily leadsto their entrance into the gastrointestinalsystem, organs remote from the depositionsite may be affected. The models developedby the Task Group on Lung Dynamics areused in this chapter as a basis for discussionof experimental data on the deposition, re-tention, and clearance of particles. Thesemodels provide a useful representation ofthe deposition and clearance mechanisms andhave been shown to yield predictions whichhave often been substantiated by experimen-tal findings.
F. REFERENCES
1. Hatch, T. F. and Gross, P. "Pulmonary Depo-sition and Retention of Inhaled Aerosols." Aca-demic Press, New York, 1964.
2.'iMorrow, P. E. "Some Physical and Physiologi-fag Factors Controlling the Fate of Inhaled Sub-
stances. I. Deposition." Health Physics, Vol. 2,pp. 366-378, 1960.
3. Davies, C. N "Inhalation Risk and Particle Sizein Dust and Mist." Brit. J.. Ind. Med., Vol. 6,p. 245, 1949. .
4. "Deposition and Retention Models for InternalDosimetry of the Human Respiratory Tract."Task Group on Lung Dynamics. Health Physics,Vol. 12, pp. 173-207, 1966.
5. Miller, W. S. "The Lung." 2nd edition. Thomas,Springfield, Illinois, 1947.
6. Krahl, V. E. "Microscopic Anatomy of theLungs." Am. Rev. Respirat. Diseases, Vol. 80,pp. 24-44, 1959.
7. Davies, C. N. "A Formalized Anatomy of theHuman Respiratory Tract." In: Inhaled Par-ticles and Vapours, Vol. 1, C. N. Davies (ed.),Pergamon Press, London, 1961, pp. 81-91.
8. Mitchell, R. I. and Tomashefski, J. F. "Aero-sols and the Respiratory Tract." Battelle Techn.Rev., Vol. 13, pp. 3-8, 1964.
9. Silverman, L., Lee, G., Plotkin, T., Sawyers, L.A., and Yancey, A. R. "Air Flow Measurementson Human Subjects with and without Respira- 24.tory Resistance at Several Work Rates." . Arch.Ind. Hyg., Vol. 3, pp. 461-478, 1951.
10. Amdur, M. 0., Silverman, L., and Drinker, P."Inhalation of Sulfuric Acid Mist by HumanSubjects." Arch. Ind. Hyg., Vol. 6, pp. 305-313,1962.
11. Altshuler, B., Palmes, E. D., Yarmus, L., andNelson, N. "Intrapulmonary Mixing of GasesStudied with Aerosols." J. Appl. Physiol., Vol.14, pp. 321-327, 1959.
12. Findeisen, W. Ober das Absetzen kieiner in derLuft suspendierten Teilchen in der menschlichenLunge bei der Atmung." Arch. Ges. Physiol., Vol.236, pp. 367-379, 1935.
13. Landahl, H. D. "On the Removal of AirborneDroplets by the Human Respiratory Tract. I.The Lung." Bull. Math. Biophys., Vol. 12, pp.43-56, 1959.
14. Weibel, E. W. "Morphontetry of the HumanLung." Academic Press, New York, 1963.
15. Landahl,_ H. D. "On the Removal of AirborneDroplets by 'the Human Respiratory Tract. II.The Nasal Passages." Bull. Math. Biophys., Vol.12, pp. 161-169, 1950.
16. Lehmann, K., Saito, Y., and Girorer, W. "Oberdie quantitative Absorption von Staub aus derLuft durch den Menschen." Arch. Hyg. Bak-teriol., Vol. 75, pp. 152-459, 1912.
17. Saito, Y. "Experimentelle Untersuchen fiber diequantitative Absorption von Staub durch Tierebei Genau Beakafintem. Staubgehalt der Luft."Arch. Hyg. Balcteriol., Vol. 75, pp. 134-151, 1912.
18. Owens, J. S. "Dust in. Expired Air." Trans.Med. Soc. (London), Vol. 45, pp. 79-90, 1923.
19. Baumberger, J. P. "The Amount of Smoke Pro-duced from Tobacco and the Absorption in Smok-ing as Determined by Electric Precipitation."
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20.
21.
22.
23.
25.
26.
27.
J. Pharmacol. Exper. Therap., Vol. 21, pp. 47-57,1923.
Sayers, R. R., Fieldner, A. C., Yant, W. P.,Thomas, B. G. H., and McConnel, W. J. "Ex-haust Gases from Engines Using Ethyl Gaso-line." U.S. Dept. of Interior, Bureau of Mines,Report of Investigations 2661, 1924, 24 pp.Drinker, P., Thompson, R. M., and Finn, J. L.Quantitative Measurements of the Inhalation,Retention, and Exhalation of Dust and Fumesby Man. I. Concentration of 50 to 450 mg percubic meter." J. Ind. Hyg. Toxicol., Vol. 10, pp.13-25, 1928.
Van Wijk, A. M. and Patterson, H. S. "ThePercentage of Particles of Different Size, Re-moved from Dust Laden Air by Breathing." J.Ind. Hyg. Toxicol., Vol. 22, pp. 31-35, 1940.Brown, C. E. "Quantitative Measurements, ofthe Inhalation, Retention, and Exhalation ofDust and Fumes by Man. II. Concentration be-low 50 mg per cubic meter." J. Ind. Hyg. Toxi-col., Vol. 13, pp. 285-291, 1931.Brown, C. E. "Quantitative Measurements ofthe Inhalation, Retention, and Exhalation ofDust and Fumes by Man. III. Factors Involvedin the Retention of Inhaled Dusts and Fumesby Man." J. Ind. Hyg. Toxicol., Vol. 13, pp.293-313, 1931.
Altshuler, B., Yarmus, L., Palmes, E. D., andNelson, N. "Aerosol Deposition in the HumanRespiratory Tract. I. Experimental Proceduresand Total Deposition." Arch Ind. Health, Vol.151 pp. 293-303, 1957.
Dautrebande, L. and Walkenhorst, W. "Ober dieRetention von Kochsaltteilchen in den Atema-gen." In: Inhaled Particles and Vapours, Vol.1, C. N. Davies (ed.), Pergamon Press, London,1961, pp. 110-121.
Dautrebande, L., Bechmann, H., and Walken-horst, W. "Lung Deposition of Fine Dust Par-ticles." Arch. .Ind. Health, Vol. 16, pp. 179-187,1957.
Dennis, W. L. "Discussion of Davies." In: In-haled Particles and Vapours, Vol. 1, C. N. Davies(ed.), Pergamon Press, London, 1961, pp. 88-91.Morrow, P. E. and Gibb, F. R. "The Deposi-tion of a Submicronic Aerosol in the RespiratoryTract of Dogs." Am. Ind. Hyg. Assoc. J., Vol.19, pp. 196-200, 1958.
. Landahl, H. D., Tracewell, T. N., and Lassen,W. H. "Retention of Airborne Particulates inthe Human Lung." III.. Arch Ind. Hyg., Vol.6, pp. 508-511, 1952.
. Lehmann, C. "The Dust Filtering Efficiency ofthe Human Nose and its Significance in theCausation of Silicosis." J. Ind. Hyg. Toxicol.,Vol. 17, pp. 37-40, 1935.
Tourangeau, F. J. and Drinker, P. "Dust Fil-tering Efficiency of the Human Nose." J. Ind.Hyg. Toxicol., Vol. 29, pp. 53-57, 1937.
28.
29.
30
31
32.
33. Landahl, H. D. and Black, S. "Penetration ofAirborne Particulates through the Human Nose."J. Ind. Hyg. Toxicol., Vol. 29, pp. 269-277, 1947.
34. Landahl, H. D. and Tracewell, T. N. "Penetra-tion of Airborne Particulates through the Hu-man Nose." II. J. Ind. Hyg. Toxicol., Vol. 31,pp. 55-59, 1949.
35. Wilson, I. B. and LeMer, V. K. "The Retentionof Aerosol Particles in the Human RespiratoryTract as a Function of Particles Radius." J.Ind. Hyg. Toxicol., Vol. 30, pp. 265-280, 1948.
36. Brown, J. H., Cook, K. M., Ney, F. G., and Hatch,T. F. "Influence of Particle Size upon the Re-tention of Particulate Matter in the HumanLung." Am. J. Public Health, Vol. 40, pp. 450-458, 1950.
37. Palm, P. E., McNerney, J., and Hatch, T. F."Respiratory Dust Retention in Small Animals.A Comparison with Man." Arch. Ind. Health,Vol. 13, pp. 355-365, 1965.
38. Kotin, F. and Falk, H. "Atmospheric Factorsin Pathogenesis of Lung Cancer." Advan. Can-cer Res., Vol. 7, pp. 475-514, 1963.
39. Morrow, P. E., Gibb, F. R., Davies, C. N., andFisher, M. "Dust Removal from the Lung Para:-chyme : An Investigation of Clearance Simu-lants." Toxicol. Appl. Pharmacol. Vol. 12, pp.372-396, 1968.
40. Dalhamn, T. "Mucous Flow and Ciliary Activityin the Trachea of Healthy Rats and Rats Ex-posed to Respiratory Irritant Gases." ActaPhysiol. Scand., Suppl. 123, 1956.
41. Dalhamn, T. "A Method for Studying the Effectof Gases and Dusts on Ciliary Activity in LivingAnimals." In: Inhaled Particles and Vapours,Vol. 1, C. N. Davies (ed.), Pergamon Press, Lon-don, 1961, pp. 315-317.
42. Antwiler, H. "Ober die Funktion des Flimmer-epithels der Luftwege inbesondere unter Staub-belastung." Beitr. Silkose-Forsch., Sonderband,Vol. 3, p. 509, 1958.
43. Hilding, A. C. "On Cigarette Smoking, Bron-chial Carcinoma, and Ciliary Action. III. Ac-cumulation of Cigarette Tar upon ArtificiallyProduced Deciliated Islands in the RespiratoryEpithelium." Ann. Otol. Phinol. Laryngol., Vol.65, pp. 116-130, 1956.
44. Hilding, A. C. "Ciliary Streaming in the Bron-chial Tree and the Time Elements in Carcino-genesis." New Engl. J. Med., Vol. 256, pp. 634-640, 1957.
45. Casarette, L. J. "Autoradiographic Observa-tions after Inhalation of Polonium** in Rats."Radiation Res. (Suppl.), Vol. 5, pp. 187-204,1964.
46. Albert, R. E., Lippman, M., Spiegelman, J.,Strethlow, C., Briscoe, W., Wolfson, P., andNelson, N. "The Clearance of Radioactive Par-ticles from the Human Lung." In: Inhaled Parti-cles and Vapours, Vol. II, C. N. Davies (ed.),Pergamon Press, London, 1967, pp. 361-378.
47. Albert,- R. E. and Arnett, L. C. "Clearance ofRadioactive Dust from the Lung." Arch. Ind.Health, Vol. 12, pp. 99-106, 1955.
48. Holma, B. "Short Term Lung Clearance in Rab-bits Exposed to a Radioactive Bi-disperse (6and 3) Polystyrene Aerosol." In: Inhaled Parti-cles and Vapours, Vol. II, C. N. Davies (ed.),Pergamon Press, London, 1967, pp. 189-203.
49. Brieger, H. and LaBelle, C. W. "The Fate ofInhaled Particulates in the Early PcstexposurePeriod." Arch. Ind. Health, Vol. 19, pp. 510-515,1959.
50. Downs, W. L. "Excretion of Uranium by. RatsFollowing Inhalation of Uranium Dioxide."Health Physics, Vol. 13, pp. 445-453, 1967.
51. Casarett, L. J. "Some Physical and Physiologi-cal Factors Controlling the Fate of Inhaled Sub-stances. II. Retention." Health, Physics, Vol.2, pp. 379-386, 1960.
52. Casarett, L. J. and Milley, P. S.41Alveolar Re-activity Following Inhalation of Particles."Health Physics, Vol. 10, pp. 1003-1011, 1964.
53. Policard, A., Collet, A., and Pregermain, S."Structures alveolaires norfaales du pneumonexamines au microscope electronique." Semaine.Hop. (Paris), Vol. 33, p. 355,1957.
54. LaBelle, C. W. and Briefer, H. "SynergisticEffects of Aerosols. II. Effects on Rate of Clear-ance from the Lung." Arch. Ind. Health, Vol. 20,pp. 100-105, 1959.
55. LaBelle, C. W. "Patterns and Mechanisms inthe Elimination of Dust from the Lung." In:Inhaled Particles and Vapours, Vol. 1, C. N.Davies (ed.), Pergamon Press, London, 1961, pp.356-368.
56. Gross, P., Pfitzer, E. A., and Hatch, T. F. "Al-veolar Clearance: Its. Relation to Lesions of theRespiratory Bronchiole." Am. Rev. Respirat.Diseases, Vol. 94, pp. 10-19, 1966.
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9
Chapter 10
TOXICOLOGICAL STUDIES OFATMOSPHERIC PARTICULATE MATTER
135
Table of ContentsPage.
A. INTRODUCTION 129B. MECHANISMS OF TOXICOLOGICAL ACTION OF PARTICULATE
MATTER 1291. Intrinsic Toxicity 1292. Absorbed Substances 1303. Reduction of the Toxicity of Irritant Gases 130
C. TOXICOLOGICAL STUDIES OF SPECIFIC PARTICULATEMATERIALS 1311. Pathological Studies of Smoke and Carbon Particles i312. Physiological Studies of Response to Particulate Material 1323. Experimental Studies of Mixtures of Irritant Gases and Particulate
Material 134D. CARCINOGENESIS 137
1. Carcinogens 1372. Polynuclear Aromatic Hydrocarbons as Carcinogens in Polluted
Atmospheres 1383. Pathology of Carcinogenesis 141
E. SUMMARY 141F. REFERENCES
List of TablesTable10-1 Effect of Exposure of Rabbits to 2 ppm Ozonized Gasoline on Re-
tention of Inhaled Soot10-2 Benzo (a) pyrene Concentrations in Several Urban and Nonurban
Areas
10-3 Benzo (a) pyrene as a Fraction of the Total Aromatic HydrocarbonContent of Several Urban Atmospheres
10-4 Effect of Various Conditions of Exposure on the Destruction ofSome Polynuclear Aromatic Hydrocarbons
10-5 Percentage Recovery of Polynuclear Aromatic Hydrocarbons from0.51A Soot Particles and from Plasma after Incubation with Plasmafor Varying Periods
142
134
138
138
139
140.10-6 Distribution of Lung Cancer by Site of Origin 141
Chapter 10
TOXICOLOGICAL STUDIES OF ATMOSPHERIC PARTICULATE MATTER
A. INTRODUCTION
Experimental toxicology, using specificatmospheric pollutants, would be the best.means for deriving air quality criteria, pro-vided that man could be used as the experi-mental animal. However, the ethical impos-sibility of performing experiments usinghuman exposures to varying concentrationsof a wide range of compounds precludes sodirect an approach. Although a limitedamount of intentional human experimenta-tion may be possible, most of the data forhuman toxocology are derived from acci-dental or occupational exposures. The use oflaboratory animals in toxicological experi-ments is more straightforward, but the ob-vious anatomical and metabolic differencesbetween the animals and man require the ex-ercise of considerable caution in applying theresults of animal exposures to human healthcriteria. Furthermore, many of the animalexperiments performed have left somethingto be desired in terms of air pollution toxicol-ogy, since the "end-point" of the experimentshas frequently been the death of -the saimalsat exposures to concentrations far in excessof those likely to be found, or tolerated, in theatmosphere. There is a great need for chronicinhalation studies to define long-term effectsoccurring over a lifespan.
The difficulties and limitations of toxico-logical studies discussed in the last para-graph should not obscure the fact that an in-creasing amount of data useful for air qualitycriteria is being amassed; it is, however, al-ways essential to bear in mind the limitationsof the data. Toxicological studies have shown.that atmospheric particles may elicit a path-ological or physiological response in at leastthree ways. First, the particle may be in-trinsically toxic; second, the presence of an
.
,...;
"inert" particle in the respiratory tract mayinterfere with tha clearance of other air-borne toxic materials; and third, the particlemay act as a carrier of toxic material. Thereis also evidence that the presence of particlesmay occasionally reduce the toxicity of asecond pollutant; this phenomenon is de-scribed briefly. From an air pollution stand-point, one of the most ubiquitous'particulatepollutants is smoke; some pathological stud-ies involving this material are presented.Studies of physiological response to irritantparticles and to mixtures of particulate mat-ter with irritant gases are described.
A final section of this chapter then dealswith carcinogenesis and atmospheric pol-lutants.
B. MECHANISMS OF TOXICOLOGICALACTION OF PARTICULATE MATFER
1. Intrinsic ToxicityFew common atmospheric particulate pol-
lutants appear to be intrinsically toxic; ofthese, the most important toxic aerosol issulfur trioxide (SO8) (either as the freeoxide, or hydrated as sulfuric acidH2SO4),which has a high degree of toxicity, at leastfor the guinea pig. Although silica (from flyash) is frequently present as a pollutant, at-mospheric concentrations are normally toolow to lead to silicosis. In recent years, how-ever, concern has been expressed over a num-ber of less common toxic particulate pollut-ants, including lead, beryllium, and asbestos.Increasing amounts of lead (as oxides andsalts) are being discharged into the atmos-phere as a result of the burning of gasolinecontaining lead additives; on the other hand,other sources contributing to atmosphericlead seem to be decreasing and, according toStoldnger and Coffin,1 toxic effects due to
129
lead do not seem to present a serious risk tothe population at large. Beryllium (as theoxide BeO) can lead to chronic pulmonarydisease with a high fatality rate. Accidentalexposures have shown that .there may be aconsiderable latency period before diseasedevelops, and some alarm has been generatedover the use of beryllium as a rocket fuel,although the rocket effluent is predominantlya "high-fired," relatively inert form of beryl-lium oxide. The situation with regard to as-bestos is also potentially serious. Brief in-dustrial or accidental exposures to asbestoscan lead, after a latency period of 40 yearsor more, to the development of diffuse meso-theliomas of the pleura or peritonium, and itis possible that sufficient levels of asbestosmight be generally present in the atmosphereto constitute a definite health hazard. Thispossibility is made more likely by the greatlyincreased use of asbestos since the occur-rence of the exposures which are only nowleading to the development of mesotheliomas.A series of autopsies has shown that an ap-preciable fraction (20 percent to 50 percent)of the population at large has "asbestosbodies" in its lungs. More detailed discussionsof both asbestos = and beryllium = toxicitymay be found in recent reviews.
Several other potential carcinogens areknown to be present as relatively minor at-mospheric pollutants; these may be particu-late in nature, and they are discussed inSection D.
2. Adsorbed SubstancesToxic substances may be adsorbed on the
surface of particulate matter, which maythen carry the toxic principle into the respi-ratory system. The presence of carbon orsoot as a common particulate pollutant isnoteworthy, as carbon is well known as anefficient adsorber of a wide range of organicand inorganic compounds. Some specific stud-ies involving mixtures of particulate matterand irritant gases are presented in SectionC-3; the present section is concerned mainlywith the general principles of adsorption anddesorption.
The role played by the affinity for the ad-sorbate by the particle is complex..A high af-finity will mean that relatively large loads of
130
adsorbate may be carried by each particle. Ifthe adsorbate in its free state is slowly re-moved from the air in the respiratory system,then the deposition of particles carrying highconcentrations may constitute a greater toxichazard, especially at the localized depositionpoints. Whether or not the effect is signifi-cant depends on the efficiency of the desorp-tion and elution process relative to that of theclearance process. The chemical nature ofboth adsorber and adsorbate, and the size ofthe adsorbing particle, all play a part in de-termining these various efficiencies, and eachsystem will show its own individual charac-teristics. Carcinogens, which may producetheir effect only after long or repeated ex-posure, present a particularly involved situa-tion, because it is not clear whether slow re-lease of small concentrations of the carcino-gen is more dangerous than the rapid releaseof larger quantities. Experimental evidenceon the elution of ..a specific series of carcino-gens is described in Section D-2.
3. Reduction of the Toxicity of IrritantGases
The finding that a preexposure to particu-late material will tend to protect animalsagainst the action of an irritant gas is not anuncommon one.
Pattie and Burgess found that, with miceand guinea pigs, the previous inhalation ofsmoke reduced the toxicity of sulfur dioxide(measured in terms of the dosage requiredto produce death). They postulated that thereduced toxicity of SO2 produced by preexrposure to smoke was due either to the actionof the smoke in reducing the volume breathed(and thus the SO2 dose received) , or to astimulation of secretions which may protectthe mucosa from the irritant action of thegas. This explanation is given weight by theirfindings that increased toxicity resulted fromthe administration of mixtures of smoke andsulfur dioxide. A similar study by Salem andCullumbine 5 indicated that the effect of kero-sene smoke on the toxicity of irritant sub-stances depended to some extent on the spe-cies of animal, althougl, the toxicity of acro-lein and acetaldehyde seemed to be decreasedin most cases.
. agner et ai.° observed that the preex-..:1
posure of mice to oil mists would protectagainst the later action of inhaled ozone andnitrogen dioxide..The greatest protection wasobtained when the oil mist was given 18hours prior to the exposure to the irritantgas; when the oil mist and irritant gas weregiven together, there was an enhancement oftoxicity. The relative degree of this enhance-ment was consistent with the known depth ofpenetration of nitrogen dioxide and ozone inthe respiratory tract and the relative solubil-ity of the two gases in mineral oil. The hy-pothesis for the protective action of the pre-treatment with oil is the formation of an oilfilm on the aveolar surface.
Again, Amdur and Devir,' using guineapigs, have observed that the presence of anaerosol of 2.5p, triphenyl-phosphate particlesat a concentration of 50 mg/m3 to 100 mg/m3lessens the increase in pulmonary flow re-sistance due to inhalation of sulfur dioxide.They then studied the effect of treatmentwith the particulate material before expo-sures to sulfur dioxide alone. This sequenceafforded excellent protection against the re-sponse to the sulfur dioxide, and the degreeof protection was related to the total amountof aerosol inhaled.
C. TOXICOLOGICAL STUDIES OFSPECIFIC PARTICULATE MATERIALS
1. Pathological Studies of Smoke andCarbon Particles
Smoke from burning bituminous coal wasused for a study on rabbits and rats bySchnurer and Haythorn.8 Four rabbits andeight rats were exposed for periods of 80days to smoke with a concentration of 125million particles/fts (4410 particles/cm3), ofwhich 8 percent was free Si02. Control ani-mals received clean filtered air. One controlrabbit and two exposed rabbits died of bron-chial pneumonia before the end of the expo-sure. One rabbit and six rats were autopsiedimmediately after exposure, and the rest atintervals up to 429 days. Lesions typical ofnonoccupational anthracosis were noted inthe lungs of the animals killed immediatelyafter exposure, while fibrous reactions de-veloped around the carbon deponita (with theformation of collagen strands) in the animals
that were examined several months to a yearafter the exposure. The authors state thatthese lung changes were analogous to thoseseen in a milder grade of bituminous pneu-moconiosis of soft-coal miners, and they alsoconcluded that the pneumonitis and fibrosiswere attributable to the carbon rather thanto the small amount of silica present. .
Schnurer P. has also attempted to comparethe response to the burning of equal weightsof anthracite coal, coke, and bituminous coal.Unfortunately, widely differing particle con-centrations were obtained from burning equalweights of fuel, so that it is impossible toplace any simple interpretation on the re-sults of the experiments.
Pattie et al.'° studied the acute toxic effectsof smoke, generated by burning tetrahydro-naphthalene in the concentration range of700 mg/m3 to 1100 mg/m3. They found thatthe median dosage to death for guinea pigsand mice lay between 147,000 mgmin/m3 to351,000 mgminims. In mice, the cause ofdeath was blockage of the air passages anddelayed death resulting from the exposurewas unusual. The guinea pigs showed hemor-rhagic lesions, and delayed deaths were morecommon. The action of smoke on rats re-sembled that on mice. No data are providedto show that unburnt tetrahydronaphthalenedid not enter the smoke stream in these ex-periments, since toxic effects are well knownfor this substance.
In the course of a study of mixtures ofsulfur dioxide and smoke, to be discussed inSection C-3, Pattie and Burgess4 reportedsome data on the effect of smoke alone onmice. The smoke was generated by a burningkerosene lamp, and its concentration wasabout 50 mg/ms. The experiment continuedfor 36 hours followed by a gap of 11 hours.The experiment was subsequently continuedfor 30 hours. There were no fatalities andnone occurred after the experiment. Histo-logical examination of the lungs slimed thatat the end of exposure the soot particles werepartly spread over the lining of the bron-chioles and alveoli and partly aggregated intopatches. There were no signs of edema, con-solidation, hemorrhage, or, emphysema. andcapillary congestion was slight. The lungswere normal except for the presence of car-
,
181
Een
-.3
bon particles, and animals killed 3 monthsafter exposure showed phagocytosis andgradual clearance of smoke from the lungs.
Salem and Cullumbine 3 also make briefmention of the exposure of mice and guineapigs to smoke from a kerosene lamp. Theanimals survived exposure to 664 mg/m3 ofsmoke for 6 hours, and autopsy revealed noobvious damage to the lungs.
The physiological effects on mice of ex-posure to carbon black by ingestion, skin con-tact, subcutaneous injection, and inhalationwere examined by Nau et al."-" Channelblack ( particle diameter 0.0250 and furnaceblack (particle diameter 0.0850 were used inconcentrations of 2.4 mg/m3 and 1.6 mg/m3respectively for the inhalation experiments.Mice, hamsters, guinea pigs, rabbits, andmonkeys were exposed for prolonged periodsto the dust, but no effect other than the ac-cumulation of carbon particles in the lungswas demonstrated.
The problem of whether exposure of ratsto coal dust or smoke would alter their sus-ceptibility to infection by Type I pneumo-cocci was examined by Vintinner and Baet-jer 15 as part of a series of studies on the ef-fect of fibrous, inert, and adsorptive dusts onsusceptibility to infection in experimentalanimals.36-18 The concentration of coal dustvaried between 400 and 850 million particles/ft3 with an average of 700 million particles/ft3. The smoke level in the chambers wouldhave been considered as "dense" on visualinspection, or equivalent to about a Number8 reading on the Ringelmann Chart. Analysesof the particulate matter in mg/m3 in thesmoke chamber averaged as follows: Totalsolids - -570, carbon-470, ash-93, silica-46, iron-15, and sulfur-9, that is, about100 times the values listed as "average com-position of susupended dust during the win-ter months for all cities." The exposuresranged from 5 days to 165 days for the bitu-minous coal dust and from 2 days to 154 daysfor the smoke. On the basis of theirextensivedata, the authors concluded that the inhala-tion of smoke did not alter the susceptibilityto infection when the organisms, either inbroth or in mucin, were administered by in-trabronchial injection. The bituminous coaldust seemed to exert a slight protective effect
132
when the organisms were suspended in mucinbut not when they were injected in a brothmedium.
Based upon the reported studies, smoke orcarbon black on its own apparently produceslittle major damage to the respiratory systemof animals even at exposure levels someorders of magnitude greater than those en-countered in polluted atmospheres.
2. Physiological Studies of Responseto Particulate Material
Certain particulate materials are pulmon-ary irritants which have been shown to pro-duce alterations in the mechanical behaviorof the lungs, the alteration being predomi-nantly an increase in flow resistance. Thiswas demonstrated by Amdur 19 for sulfuricacid, and by Amdur and Corn 20 for am-monium sulfate, zinc sulfate, and zinc am-monium sulfate, using the guinea pig as anassay. animal. (The decreased flow rates ob-served by Amdur, Silverman, and Drinker 23
in human subjects exposed to sulfuric acidmist probably reflect an increase in flow re-sistance, although, since the resistance wasnot measured in those experiments, such astatement cannot be conclusive.) A series ofpapers making use of the increase in pulmon-ary flow resistance as an assay tool has beenpublished by Amdur,22-2/ and "response" toan irritant in discussion of her work general-ly refers to this increase.
Nadel et al.2" report a correlation betweenthe alterations in pulmonary mechanics andactual anatomical change in cats exposed toaerosols of histamine and zinc ammoniumsulfate. The authors discuss the physiologicalmechanisms which may operate to bringabout such alterations in pulmonary me-chanics.
In connection with a study of the effect ofvarious aerosols on the increase in pulmonaryflow resistance in guinea pigs produced bysulfur dioxide, Amdur and Underhill 22 firstexamined the response to the aerosols alone.These aerosols included spectrographic car-bon at 2 mg/m3 and 8 mg/m3, activated car-bon at 8.7 mg/m3, manganese dioxide at 9.7mg/m3, open hearth dust at 7.0 mg/m3, ironoxide (Fe208) at 11.7 mg/m3 and 21.0 mg/m3,manganous chloride and ferrous sulfate at
4i1-
1 mg/m3. and sodium orthovanadate at 0.7mg/m3; the particle sizes were less than 0.5p.Standard one-hour exposures were used inthis routine bioassay method, with the ex-ception of the iron oxide exposure, whichwere extended to two hours. In no instancedid any of the aerosols produce an alterationin flow resistance. The failure of the aerosolsto produce an increase in resistance in theseexperiments suggests that if they cause bron-chial constriction, it must be only in extreme-ly high concentrations. From the point ofview of air pollution toxicology, none of themwould be classed on this basis as pulmonaryirritants. An uncharacterized "fly ash" froman oil-fired burner was also tested and provedinert;
At a concentration of 1 mg/m3, ferric sul-fate aerosol produced a 77 percent increase inflow resistance in a group of 15 animalswhich was statistically significant at the levelof P<0.001. Ferric sulfate, in distinction toferrous sulfate, must be clasged as an irri-tant.
On the other hand, Dautrebande and Du-Bois 29' 29 have reported constriction and in-creased airway resistance in isolated guineapig lungs and in human subjects with a widevariety of supposedly "inert" particulate mat-ter. The relationship of their results to Am-dur's work is not clear. since Dautrebande'sparticle concentrations appear to be ab-normally high. Total lung capacity and vitalcapacity were not altered by the inhalationof particulate material in healthy subjects,but the vital capacity in patients with 'pul-monary disease was reduced by the inhala-tion of particulate materials. it is interestingin this connection that guinea pigs with aninitially high pulmonary flow resistanceshowed a greater response to low concen-trations of irritant aerosols or of inert aero-sol-irritant gas combinations than .animalswith average control flow resistance values."
The possibility that the conflict betweenAmdur's and Dautrebande's work may beresolved in terms of the doses involved isgiven credence by studies which suggest thathuman response to coal dust may be dose-related." Coal dust clouds similar to those inmines have been produced in the laboratory,and the number and weight of respirable par-
tides have been measured. Clouds containing8 mg/m3, 9 mg/m3, 19 mg/m3, 33 mg/m3, and50 mg/m3 dust in the size range of 1p to 7pwere used. Normal subjects inhaled the dustfor 4 hours, and airway resistance was meas-ured with a body plethysm'ograph. No chang-es were obtained after the inhalation of coaldust from clouds containing 8 mg/m3 or 9mg/m3; but with concentrations of 19 mg/m3,33 mg/m3. and 50 mg/m3, significant in-creases in airway resistance occurred andthe response was correlated with the quan-tity of- dust. One hour after exposure ceased,the airway resistance was about two-thirdsback to normal. With the two highest concen-trations, the respiratory rate increasedthroughout the 4 hours, and subjects com-plained of difficulty in breathing after one totwo hours. It would appear that if 8 mg/m3or 9 mg/m3 produced no lung function change'in a 4-hour period, the material (cold dust)and perhaps other "inert" particulate matterwould be unlikely to do so at any concentra-tions likely to occur in air pollution. In Chap-ter 1, Table 1-2 shows a. maximum geometricmean concentration of urban particulates in1961 to 1965 of 180 µg /m3.
Particle size may .play an important partin determining the potency of an irritant.For example, at a mass concentration of 1.4mg/m3 to 1.9 mg/m3, sulfuric acid mist of0.8p produces a 51 percent increase in pul-monary flow resistance in guinea pigs ascompared to control values," and zinc am-monium sulfaik particles of 0.84p produce a21 percent increase." If the zinc ammoniumsulfate size is 0.8p. the corresponding in-crease in pulmonary flow resistance is 180percent." The studies on zinc ammoniumsulfate were carried out by Amdur andCorn 20 with nonhomogeneous aerosols withmean sizes by weight of 0.24p, 0.51p, 0.74p,and 1.4p., at several concentrations. As theparticle size decreased over the range 1.4,to 0.29p, the response to an equal mass con-centration rose. When dose-response curvesof percent increase in flow resistance againstconcentration in mg/m3 were plotted for thedifferent particle sizes, the slopes increasedas the particle size decreased. A similar studywas undertaken by Amdur and Creasia 33using m-terphenyl as the aerosol (size range
141 188
I.
0.3, to 2.0p.) ; this aerosol does not absorbwater during passage through the respira- .
tory tract. An essentially, identical pattern tothat seen for zinc ammonium sulfateemerged, with the irritant potency increasingwith decreasing particle size, and the slopesof the dose-response curves steeper thanthose for the smaller particles. All of theparticles used in these studies fall withinthe "respirable size range." The possible im-plications for air pollution are:
. 1. Particles below 11i mAy have greaterirritant potency than larger species, .
and2..A small increase in concentration
could produce a greater-than-linearincrease in irritant response whenthe particles are smaller than 44.
The effect of particulate matter on clear-ance mechanisms has already been men-tioned. The deposition of particles affectsmucous secretion and ciliary action mostmarkedly at branchings; e.g., miniatureridges throughout the tracheobronchial treeas contrasted with intervening areas, and itis in the ridge areas that alterations in themorphology are initially most intense andprolonged and ultimately irreversible. Theadverse effect is manifested by a slowing ofthe flow of the mucous stream, alteration inthe physical and chemical properties ofmucus, and changes in ciliary action.
Examination of sections of respiratoryepithelium removed from the lungs revealhyperplastic and metaplastic changes earli-est at these sites. The exaggerated effect of
Table 10-I.EFFECT OF EXPOSURE OF RABBITS
the impingement of irritants on respiratoryepithelium at branch points taken togetherwith less efficient clearance is consistent withthis result. Thus, abnormal retention and ac-cumulation of soot (and possibly carcinogenicparticles) may occur, especially in segmentalbronchi. The accompanying peribronchialand peribronchiolar inflammatory responsefurthe in(rferes with physiologic mechan-isms o deense.
Experimental confirmation of enhanced re-tention in the presence of irritant materialis to be found in the work of Tremer et al.,"who exposed rabbits first to synthetic smogand then to soot. The results are shown inTable 10-1.
.
The main conclusions of this section are:1.. The predominant physiological effect
of irritants is to increase pulmonaryflow resistance;
2. Exceptionally heavy loads of rela-tively inert particles may cause someincrease in flow resistance; and
3. The intensity of physiologic responsemay increase with a .decrease in par-ticle size for any given irritant.
. .3. Experimental Studies of Mixtures ofIrritant Gases and Particulate MaterialThe possible influence of inert particulate
matter on the toxicity of irritant gases hasbeen the subject of considerable specula-tion 35-37 and a limited amount of experimen-tal work. Such interaction of gaseous andparticulate pollutants might be importantto understanding the complicated toxicologi-cal picture of the air pollution disasters.
TO 2 PPM OZONIZED GASOLINE ON RETENTIONOF INIIALED SOOT.
SpecimenSmog
exposure,hours
Room air(recovery),
hours
Sootexposure,
hoursRoom air(recovery),
hours
Soot inlung,mg
No recovery period after smog exposure:Control 0 0 1 0 3.7Animal No. 1 1 0 1 0 7.9Animal No. 2 0 1 24 6.4With varying recovery periods:Control 0 0 1 0 1.1Animal No. 1 1 4 1 0 7.4Animal No. 2 1 8 1 6.2Animal No. 3 1 24 1 0 2.0
1 lM
$41 The first experimental evidence that aninert aerosol could an'.alter the response to airritant gas was presented in 1939,3° whenit visa reported that concentrations of mus-tard gas which were relatively harmless torats would produce pulmonary edema. anddeath when administered in combinationwith an inert aerosol (sodium chloride). Itwas postulated that the adsorption of gason the particles had increased the amountof irritant vapor reaching the critical tar-get areas of the lung. Dautrebande and hisco-workers 33' 4° studied the sensory responseof human subjects to pollutants thought tobe constituents of the Los Angeles. smog andfound that the presence of particles of so-dium chloride, oil mist, or smoke, increasethe irritation of eye, nose, and throat by sul-fur dioxide, formaldehyde, and other gaseouspollutants.
LaBelle et al.41 studied the effect of par-ticulate matter on the survival time of miceexposed to formaldehyde, acrolein, and ox-ides of nitrogen. The particles used includedtriethylene glycol, ethylene glycol, mineraloil, glycerin, sodium chloride, two commer-cial filter grades of diatomaceous earth, anda commercial silica gel. From theoreticalconsiderations, the probable percent penetra-tion of the upper respiratory tract by vari-ous gases was calculated. If the gas pene-trated to a greater extent than the particles,then adsorption on the particles would de-crease the amount of irritant gas reachingthe lungs and the toxicity would decrease.Such a situation exists with oxides of nitro-gen. Conversely, if the gas did not readilypenetrate the upper respiratory tract,. ad-sorption on small particles would tend tocarry more gas to the lungs and thus in-crease the toxicity. Such a situation existswith formaldehyde. The theoretical calcula-tions coincided with experimental results inover 70 percent of the gas-particle combina-tions. The theory partially explains the po-tentiation of irritant gases by particulatematerial (often termed a synergistic effect),but subsequent research has shown that theproblem is not as simple as had been as-
particles. Ammonia is a highly soluble gas,so that synergism would have been predictedby LaBelle et al.41 Rats were exposed for60 days to 100 ppm ammonia alone, 7 mg/macarbon alone, and to 119 ppm ammonia plus3.5 mg/ma carbon. The carbon particleswere 95 percent smaller than 3 µ and 65percent smaller than 1 A. In the group ex-posed to both ammonia and carbon, there wasa high frequency of mucosal damage, and theciliary activity seemed to be significantlyimpaired. The trachea of rats exposed toammonia alone showed less severe damage,and the trachea was histologically normal inabout 80 percent of the rats exposed to car-bon alone.
Boren 43 exposed mice to carbon alone, tonitrogen dioxide, and to carbon which hadpreviously been exposed to nitrogen dioxide.He stated that around 550 mg of nitrogendioxide was adsorbed per gram of carbon.Samples of air taken from the chamber dur-ing the exposure of mice to carbon with ad-sorbed nitrogen dioxide indicated that therewas about 25 ppm to 30 ppm free nitrogendioxide. Although this is a high concentra-tion of nitrogen dioxide, mice exposed to evenhigher concentrations (250 ppm) of nitro-gen dioxide alone developed pulmonary ede-ma, but neither single nor repetitive ex-posure produced parenchympi lung lesions.Control mice and mice exposed to carbonalone showed no anatomic abnormality ofthe lungs. Mice exposed to the carbon withadsorbed nitrogen dioxide developed focaldestructive pulmonary lesions. The expo-sures in this group were 6 hours per day,5 days a week, for 3 months.
The typical lesions of pneumonitis wereobserved by Gross et al." in the lungs ofhamsters,s rats, and guinea pigs exposed toa "sufficiently large number of carbon par-ticles with either adsorbed sulfur dioxide ornitrogen dioxide." Exposure was 8 hoursper day, 5 days per week, for 4 weeks. Theparticle size of the carbon, and the meaningof the phrase "a sufficiently large numberof carbon *particles" were not given. Therewas no record of the amount of either gas
sumed, adsorbed by the activated carbon particles.A synergistic effect was reported by Dal- Histological sections were from animals
hamn and Reid with ammonia and carbon killed about a month after the end of ex-
185
posure, whereby it is concluded that the le-sions were persistent. They were concen-trated in the regiOns of the respiratory bron-chioles and alveolar dusts and consisted ofcellular wall thickening.
Pattie and Burgess 4 studied the effect ofmixtures of sulfur dioxide and smoke onmice and guinea pigs. Their concentrationsof sulfur dioxide were in the range of 2,700mg/m3 to 12,000 mg/m3 (900 ppm to 4,000ppm), and the smoke concentrations were inthe range of 50 mg/m3 to 135 mg/m3. Theirend point was the dosage required to producedeath. With concentrations of this magni-tude, the results obtained have little appli-cability to air pollution criteria. Althoughthey found that the lethality of mixtures ofsulfur dioxide and smoke was greater thanthe lethality of the sulfur dioxide alone, theyconsidered the effect to be a simple additiveone resulting from the action of smoke inblocking the bronchi and alveoli.
Salem and Cullumbine 5 studied the effectof kerosene smoke on the acute toxicity ofsulfuric acid, sulfur dioxide, acrolein, andacetaldehyde in guinea pigs, mice, and rab-bits. As in the work by Pattie and Burgess,*the concentrations were many magnitudesabove those found in air pollution episodes.The administration of smoke prior to theexposure to the irritant substances did notalter the toxicity, although the -effects ofsmoke on the toxicity of the irritants werehighly variable when the two agents weregiven simultaneously. In guinea pigs, thetoxicity of sulfuric acid was increased by thepresence of smoke, the toxicity of acetalde-hyde and sulfur dioxide was decreased, andthe toxicity of acrolein was unchanged.. Inmice, the toxicity of sulfur dioxide was in-creased, while that of acetaldehyde and acro-lein was decreased. In rabbits, the toxicityof acrolein and acetaldehyde was decreasedby the smoke. The end point in all cases wasthe mean fatal dose.
A series of studies of the effect of hygro-scopic particles on physiological response toirritants has been undertaken by Amdur,22-27using the pulmonary flow resistance tech-nique. It was found initially that the re-sponse to sulfur dioxide was potentiated byparticles of sodium chloride below 1 it, but
186
not by 2.5 -s particles, at concentrations ofabout 10 mg/m3. With sulfur dioxide 24 andwith formaldehyde 25 as irritants, decreasingthe concentration of the aerosol, or the totaldose of aerosol by shortening the exposuretime," decreased the degree of potentiationobserved from the addition of sodium chlo-ride. The hypothesis of LaBelle et a/.0 thatirritant gases with high water solubilitywould be potentiated by particles did notexplain adequately the data obtained. Sul-fur dioxide, formaldehyde, acetic acid, andformic acid all have high water solubility,but it was found that the first two were po-tentiated by sodium chloride 23' 24 and thatthe latter two were not.". 27 Although bothsulfur dioxide and formaldehyde were po-tentiated by sodium chloride, there are dif-ferences which suggest that the guidingmechanism in the case of sulfur dioxide maybe chemical change and for formaldehydemay involve surface adsorption."
Another paper 2, examines further the ef-fect of various physical and chemical factorson the potentiation of sulfur dioxide by par-ticulate material. The degree of potentiationobserved could be correlated to some extentwith the solubility of sulfur dioxide in thesolutions of sodium chloride, potassium chlo-ride, and ammonium thiocyanate.
Aerosols of soluble salts of ferrous iron,manganese, and vanadium, which had beenshown by Johnstone and co-workers 45' 46 tobe capable of catalyzing the conversion ofsulfur dioxide to sulfuric acid when theywere present as nuclei of fog droplets,showed a major potentiating action wherepresent at concentrations of about 1 mg/m3.On the other hand, dry manganese dioxide,activated or spectrographic carbon, iron ox-ide fume, open hearth dust, and triphenylphosphate did not alter the response evenwhen present in concentrations of 8 mg/m3to 10 mg/m3.
It is clear from the data presented 22 thatall particulate material does not potentiatethe response to sulfur dioxide any more thanone particulate (sodium chloride) has po-tentiated the response to all irritant gasestested. Both solubility of sulfur dioxide ina droplet and catalytic oxidation to sulfuricacid play a major role in the observed poten-144...4 r.,
tiation of sulfur dioxide by certain particu-. late matter.
D. CARCINOGENESIS.
1. Carcinogens
The incidence of cancer, and the insidiousnature of the onset of malignant cell activity,together make essential the utmost effort indetermining whether factors associated withair pollution can lead to increased occurrenceof lung cancer in susceptible individuals, orto increased susceptibility to cancer in thepopulation at large. In various parts of theworld, and especially in the United States,the relative mortality due to lung cancer hasbeen increasing!? Furthermore, urban resi-dents exhibit a greater liability to the de-velopment of lung cancer than do those liv-ing in rural areas," and data from severalinvestigations suggest that the epidemiologi-cal association between urban residence andlung cancer is of pathogenetic signifi-cance.45-51 The association between lung can-cer and cigarette smoking is too well docu-mented to need further amplification here.There is, however, one feature common toboth air pollution and cigarette smokingstudies which should be emphasized. In nocase, for the reasons explained in the intro-duction to this chapter, has a suspected car-
, cinogen in fact been demonstrated experi-mentally to produce a lung tumor in man,although the epidemiological considerationsto be developed in the next chapter may wellshow a significant association between thesuspected material and cancer. Thus, sub-stances such as the polynuclear aromatic hy-drocarbons (of which benzo (a) pyrene, BaP,is the prime example) may or may not pro-duce lung cancer in man. However, theydo increase tumor incidence in laboratoryanimals and, in addition, have produced ma-lignancies when in combination with spe-cific particles or viral infection. The mini-mum, possible risk should always be taken -
with a potentially toxic substance whose ef-fect may appear after a long period of la-tency. The bulk of the. ensuing discussion istherefore based on the hypothesis that carci-nogens effective in animals may be siva&cant in increasing human malignant tumor
incidence, and the word "carcinogen' willbe used without qualification..
A portion of the organic material presentin the atmosphere as suspended particles(Table 1-2) may be carcinogenic, and carci-nogenic materials have been identified in theatmosphere of virtually all large cities inwhich studies have been conducted. The in-complete combustion of organic matter is oneof the major sources of such substances; thephotochemical reaction products of aliphaticand aromatic constituents of gasoline in thepresence of the atmospheric gases also pos-sess some potency for generating tumors ex-perimentally.
Chemical and physical studies of pollutedurban air have been paralleled by carcino-genic investigations using skin painting, sub-cutaneous injection, and inhalation tech-niques. The carcinogenicity (as measuredby these techniques) of extracts of mate-rials collected. from air as well as such pol-lutant sources as chimney soots, road dusts,and vehicular exhausts, has been establishedby many investigators. It should be notedfirst that, in many cases, use was made ofmite (A-strain) particularly susceptible totumor development; and second, only two ofthe studies, those involving ozonized gaso-line, used inhalation as a route df adminis-tration. The observed response in the caseof A-strain mice inhaling ozonized gasolinewas the relatively rapid development of mul-tiple adenomas in the lung which, althoughtumors, are not malignant.52
More recently, sequamous cell cancers ofthe lung were induced in C57 black mice fol-lowing infection with influenza virus andcontinuous exposure to an aerosol of ozon-ized gasoline. The tumors produced werehistologically identical with those observedmost frequently in man."
Measurable concentrations of inorganicsubstances, such as metal dusts and asbestos,demonstrated to be occupationilly associatedwith increased liability to lung cancer de-velopment, are also emitted into the atmo-sphere.54-50 Additional laboratory experi-mentation is needed to'verify such carcino-genic potential relative to interacting effectsand respective ambient atmospheric concen-trations.
1
,g
A
187
2. Polynuclear Aromatic Hydrocarbons asCarcinogens in Polluted Atmospheres
Polynuclear aromatic hydrocarbons arecommonly regarded with extreme suspicionas possible carcinogens, and much of theexperimental work performed has concernedthese compounds. This section deals withthe presence and stability of the hydrocar-bons in the atmosphere, and with their elu-tion from soots on which they may be ad-sorbed.
The concentration of benzo (a) pyrene(BaP) as a representative carcinogenic hy-drocarbon in selected urban and nonurbanareas within the United States is shown inTable 10-2; 61 in Table 10-3,62 the benzo(a)-pyrene content is given as a fraction of the
Table 10-2. BENZO(A)PYRENE CONaSNTRA-TIONS IN SEVERAL URBAN AND NONI.THBANAREAS.
State plg BaP/1000m° air
Urban Nonurban
Alabama 24 0.076Indiana 39 1.8Maryland 14 0.70Missouri 54 0.025North Carolina 39 0.26Oregon 8 0.01Pennsylvania 61 1.9South Carolina 24 1.1
Table 10-3.BENZO(A)PYRENE AS A FRACTIONOF THE TOTAL AROMATIC HYDROCARBONCONTENT OF SEVERAL URBAN ATMOS-PHERES
CityBaP fraction of
total aromatic hydrocarbon, pg/g
-
Lot 19 Lot 20
Atlanta 1,800 1,900Birmingham 2,300 3,400Cincinnati 2,800 5,200Detroit 3,800 4,600Los Angeles 660
i
_260
Nashville 5,900 4,900New Orleans 2,100 1,600Philadelphia 2,500San Francisco 680 290
188
total aromatic hydrocarbon content of airpollutants of nine American cities.
The physical stability of aerosols in pol-luted atmospheres has already been describedin general terms (Chapter 1). Chemically,benzo(a)pyrene seems to be relatively stableand, even in the presence of a strongly oxi-dizing atmosphere, such as that found inphotochemical smog characteristic of LosAngeles, the rate of disappearance of ben-zo(a)pyrene is smaller than that of manyother hydrocarbons. Table 10-443 shows thedestruction under certain conditions of ex-posure of various polynuclear aromatic hy-drocarbons present in air.
Polynuclear aromatic hydrocarbons mayexist in the atmosphere adsorbed on carrierparticles as well as in their free state. Aswas mentioned in Section C-2, in the respira-tory system, particle size influences the rateand extent of elution of adsorbates eitherinto the macrophages, or onto the respira-tory epithelium. Polycyclic aromatic hydro-carbons cannot be readily eluted from sootsof very small particle size; in fact, particleswith an average diameter of less than 0.04 N.
will remove these compounds from their im-mediate environment because of high sur-face adsorption. Particles above 0.04-p. aver-age size range will generally release adsorbedaromatic polycyclic hydrocarbons in thepresence of appropriate solvents, which in-clude plasma and cytoplasmic proteins. Asparticle size increases, release becomes morerapid and greater in extent. The elution ofpolycyclic aromatic hydrocarbons from 0.5-p.soot particles after incubation with plasmafor various time intervals is shown in Table10-5."
In studies on skin carcinogenesis, Falkand Steiner,66 using commercial carbonblacks, related the biological activity of ad-sorbed carcinogens to the size of the sootparticle and the presence of natural elutingsubstances at the site of deposition. Theyadvanced the principles of natural and con-ditional carcinogens, of solvent elution, andof adsorption, to explain some clinical andepidemiological observations of human skinand lung cancers, and of the role of preced-ing pathological lesions in predisposing topulmonary tumors.
Table 10-4.EFFECT OF VARIOUS CONDITIONS OF EXPOSURE ON THE DESTRUCTION OF SOMEPOLYNUCLEAR AROMATIC HYDROCARBONS
Percent destroyed
Pure unadsorbed Adsorbed on soot
Hydrocarbons By airin dark
By airin light
By smogin light
By airin ligh .v By smog
Hours
24 48 24 48 1 48 1
Compound X 100 100 100 12 72Anthanthrene 44 49 42 44 5 55Phenanthrene 39 61 34 60Pyrene 24 43 20 42 83 1 58Fluoranthene 17 20 16 24 59 4 593, 4 Benzpyrene 0 0 21 22 50 10 181, 2 Banzpyrene 7 511, 12 Benzperylene 0 0 _ 0 0 27 0 67Coronene 0 0 0 0 5Chrysene 0 0 11 0 15
The interaction o_ f carcinogens with otherparticulate agents has been studied toxico-logically, utilizing laboratory animals. Ex-periments have shown that the addition ofseemingly inert particulates Jo carcinogensresults in the production of malignant neo-plasms in the lung. Pylev 66 produced anappreciable incidence of lung cancers in ratsby the intratracheal administration of 9,10-dimethy1-1, 2 benzathracene (DMBA) in-corporated with india ink in a 4-percentcasein solution, whereas Gricute " was un-successful with the same material when itwas suspended only in physiological saline.Saffiotti el.'" has produced a variety of ma-lignant tumors in the lungs of hamsters byintratracheal instillation of saline suspen-sions of BaP ground together with hematite(Fe208) as a carrier dust in amounts equiv-alent to 3 mg of each chemical, once weeklyfor 15 injections. Not only was a high in-cidence of lung cancers produced but alsothese lung cancers mimicked all the variouscell types seen in human cancers, i.e., squa-mous cell carcinoma, anaplastic carcinoma,adeno-carcinoma, and even tracheal cancers.Dose-response effects. were suggested, aswere indications that a single high dose
could induce cancers in this system." Ac-ording to Saffiotti et at." the increased ac-
tion for the carcinogen is thought to bebrought about by its adherence to the fineinert particulate which in turn carries itthrough the respiratory bronchioles andalveoli into the lung parenchyma. The carci-nogens may then be eluted from the particu-lates and spread diffusely to reach the targettissue. They infer that there is also a re-duction in the speed in which BaP is re-moved from the respiratory tract broughtabout by the hermatite dust. Shabad et al.'1have reported that when india ink was in-cluded in the inoculum, BaP was eliminatedmore slowly from the lung. One must con-sider the possibility that the carrier materialitself might be contributing some effect.Faulds and Stewart" reported increased in-cidence of carcinoma in the : lungs of hema-tite miners. However, it is difficult to assessthe exact role of iron in such a complicatedexposure situation, since silica and otherdusts are certain to be present. Bonseret al." suggest. that iron oxide may playrole in converting the fibrogenic effect ofsilica into a carcinogenic process. Haddowand Horning " have reported that the car-
f 139
1.47
Table 10-5.PERCENTAGE RECOVERY OF POLYNUCLEAR AROMATIC HYDROCARBONS FROM 0.5ASOOT PARTICLES AND FROM PLASMA AFTER INCUBATION WITH PLASMA FOR VARYINGPERIODS.
Compound Concentration,vg /mg Soot
Incubation time. hours
Fraction 1.6 16 96 192
Percentage recovery
Pyrene 8.4 Soot 9 34 9 6Plasma 81 61 60 61Total 90 96 69 67
1-7Fluoranthrene 1.0 Soot trace present 0 presentPlasma 100 present present presentTotal 100
Compound-X 2.8 Soot 0 trace 0 0Plasma 100 98 present 89Total 100 98 89
1,2-k mpyrene 2.9 Soot trace 17 0 0Plasma 62 41 21 21Total 62 68 21 21
8,4-Benzpyrene 1.7 Soot 18 41 6 18Plasma 82 69 28 18Total 100 100 29 86
1,12-Benzperylene 9.2 Soot 81 67 6 11Plasma 66 88 16 18Total 97 100 20 24
Anthanthrene 2.4 Soot 26 64 trace 18Plasma 64 88 17 18Total 79 87 17- 20
Coronene 10.0 Soot 40 66 12 15Plasma 86 26 8 10Total 76 92 20 26
cinogenic action of an iron-dextran complexcannot be entirely explained by the dextrancontent alone. Consequently, iron cannot beexcluded as a possible contributing factoror cofactor in cancer production. Epsteinet a1.75 have recently applied methods em-ploying the injection of crude benzene-solu-ble extracts of atmospheric particulate intosuckling mice. The total dosages adminis-tered ranged from 5 to 55 mg and produceda high incidence of tumors in surviving miceas compared to controls. At 50 weeks post-inoculation, a variety of tumors was evi-dent, the most significant being lymphomas,
mas. In mature mice injected subcutaneous-ly with carcinogens, the tumors usually de-velop in the vicinity of the site of inocula-tion. However, in newborn mice, the tumorsfrequently develop at distal points such asthe liver, lungs, or lymph nodes.
More recently, Kuschner '76 has deinon-strated the interaction of a known carcino-gen with the gaseous air pollutant, SO,. In-halation exposures of rats indicated that SO2,alone, produced proliferative and metaplasticchanges in the bronchial epithelium; benzo-(a) pyrene, alone, failed to cause the develop-ment of tumors, but the inhalation of benzo-
hepatomas, and multiple pulmonary adeno- (a) pyrene in the presence of SO2 caused the
development of bronchogenic squamous cellcarcinoma.
3. Pathology of Carcinogenesis
Rather little experimental evidence isavailable on the pathology of carcinogenesisfollowing exposure to air pollutants; muchmore experimentation has been carried outin relation to smoking and lung cancer. Theresults of the extensive work on the lattertopic by Auerbach et al." are reported brieflybecause of the possible similarities betweencarcinogenic mechanisms in cigarette smok-ing and air pollution. The authors describea series of changes which are characterizedby loss of cilia, increase in the number ofcell rows, and the presence of atypical cellsin the thickened epitheliuni. Their findingssuggest a progression of changes from ini-tial goblet cell hyperplasia to metaplasia,metaplasia with atypism, carcinoma in situ,and invasive cancer. Their data further sup-port the epidemiologic observation of a doseresponse to cigarette smoke. Carnes 78 alsoobserved a clear and pronounced associationbetvveen the extent of epithelial change andexposure to pollutants, and emphasized thesimilarity of epithelial changes in man to"hyperplasia and other changes in the bron-chial epithelium of mice." Indistinguishablehistologic counterparts can be identified inboth man and experimental animals.
The sequence of hyperplasia, metaplasia,metaplasia with atypical change, cancer insitu, and invasive cancer is likely to occurfirst at sites of impingement and particulateretention. In experiments with animals, par-ticle deposition and retention occur , mostreadily in the more distal segments of thetracheobronchial tree, a result which ap-peared at first to be incompatible with earlyclinical and pathologic observations that pri-mary bronchial carcinomas originated chieflyin the main stem bronchi. Early clinical ob-servations, however, included a majority ofcases in which tumor size was great andpoint of origin was difficult to ascertain, andrecent reports question the concept that mostprimary lung cancers are hilar or central inorigin. For example, Table 10-6 shows the.distribution of lung cancer by sites of origingiven by Kotin."
I. 1
Table 10-6.DISTRIBUTION OF LUNG CANCERBY SITE OF ORIGIN
Site of originPercentage
ofincidence
Main bronchus (including intermediate) 11Lobar bronchus 29Segmental bronchus 29Segmental area (i.e., peripheral tumor) 31
E. SUMMARY
This chapter reviews toxicological studiesof various types of particulate matter knownto be present in ambient atmospheres. Thesestudies are primarily concerned with thedisciplinary areas of pathology, physiology,and carcinogenesis. In addition, the mecha-nisms of the toxicological action of particu-late matter are discussed and considerationsconcerning mixtures of irritant gases andparticulate matter are given proper empha-sis. To date, studies utilizing laboratory ani-mals have, in the main, been concerned withlevels of particulate materials far in excessof ambient concentrations. Although directextrapolations from the laboratory animalto man are impossible, animal experimenta-tion is useful and necessary for rapidly de-fining the toxicological mechanisms of ac-tion and for pinpointing the primary bio-logical systems affected by a specific particu-late material alone or in the presence of anirritant gas. Findings obtained from animalexperimentation can be tested under com-munity conditions with human populationsvia epidemiological studies.
Particulate matter may exert a toxic effectvia one or more of three mechanisms:
1. The particle may be intrinsically. toxic due to its inherent chemical
and/or physical characteristics;2. The particle may interfere with one
or more of the clearance mechanismsin the respiratory tract;
3. The particle may act as a carrier ofan adsorbed toxic substance.
The last of these mechanisms can lead to a"potentiating" effect in which particles con-taining an adsorbed toxic substance increasethe physiological response to the adsorbed
141
substance to a level above that which onewould expect if the substance were presentin the absence of the particle. Conversely,prior exposure of an animal to particulatematter can sometimes afford a degree of pro-tection to subsequent exposure to irritantgases. Particle size and dust load both con-tribute toward determining the toxicity ofany specific chemical substances: reductionin particle size generally increases toxicity,while even an "inert" particle may elicittoxic responses when present in high enoughconcentrations. Finally, it has been clearlydemonstrated that a number of substances(metal dusts, asbestos, polynuclear aromatichydrocarbons, etc.) known to be carcinogenicin animals are present in polluted atmos-pheres. When linked with urban-rural dif-ferences in lung cancer frequency revealedfrom epidemiologic investigations, this evi-dence indicates that such substances in urbanpolluted atmospheres may be potential car-cinogens for the exposed human population.
F. REFERENCES
1. Stokinger, H. E. and Coffin, D. L. "BiologicEffects of Air Pollutants." In : Air Pollution,Vol. I, A. C. Stern (ed.), Academic Press, NewYork, 1968, pp. 445-546.
2. Selikoff, and Hammond, C. "Tabular DataAnalysis of the Evidence Suggesting GeneralCommunity Asbestos Air Pollution." Preprint.(Presented at the Air Pollution Medical Re-search Conference, Denver, Colorado, July 1968.)Presented at the Air PolIntion Medical ResearchConference, Denver, Colorado, July 1968.
3. "BerylliumIts Industrial Hygiene Aspects."H. E. Stokinger (ed.), Academic Press, NewYork, 1966.
4. Pattie, R. E. and Burgess, F. "Toxic Effects ofMixtures of Sulphur Dioxide and Smoke withAir." J. Pathol-Bacterial., Vol. 73, pp. 411-419,1957.
5. Salem, H. and Cullumbine, H. "Kerosene Smokeand Atmospheric Pollutants." Arch. Environ.Health, Vol. 2, pp. 641-647, 1961.
6. Wagner, W. D., Dobrogorski, 0. J., and Stokin-ger, H. E. "Antagonistic Action of Oil Mistson Air Pollutants." Arch. Environ. Health, Vol.2, pp. 523-534, 1961.
7. Amdur, M. 0. and Devir, S. E. Unpublisheddata.
8. Schnurer, L. and Haythorn, S. R. "The Effectsof Coal Smoke of Known Composition on theLungs of Animals." AM. J. Pathol., Vol. 13,pp. 799-810, 1937.
142
9. Schnurer, L. "Effects of Inhalation of Smokefrom Common Fuels." Am. J. Public Health,Vol. 27, pp. 1010-1022, 1937.
10. Pattie, R. E., Wedd, C. D., and Burgess, F. "TheAcute Toxic Effects of Black Smoke." Brit. J.Ind. Med., Vol. 16, pp. 216-220, 1959.
11. Nau, C. A., Neal, J., and Stembridge, V. "AStudy of the Physiological Effects of CarbonBlack. I. Ingestion." Arch. Ind. Health, Vol. 17,pp. 21-28, 1958.
12. Nau, C. A., Neal, J., and Shembridge, V. "AStudy of the Physiological Effects of CarbonBlack. H. Skin Contact." Arch. Ind. Health,Vol. 18, pp. 511-520, 1958.
13. Nau, C. A., Neal, J., and Stembridge, V. "AStudy of the Physiological Effects of CarbonBlack. III. Adsorption and Elution Potentials."Arch. Environ. Health, Vol. 1, pp. 512-533, 1960.
14. Nau, C. A., Neal, J., Stembridge, V., and Cooley,R. N. "Physiological Effects of Carbon Black.IV. Inhalation." Arch. Environ. Health, Vol. 4,pp. 15-431, 1962.
15. Vintinner, F. J. and Baetjer, A. M. "Effect ofBituminous Coal Dust and Smoke on the Lungs.
- Animal Exptriments." Arch. Ind. Hyg., Vol. 4,pp. 206-216, 1961.
16. Baetjer, A. M. and Vintinner, F. J. "The Ef-fects of 'Silica and Feldspar Dusts on Suscepti-bility to Lobar Pneumonia. Animal Experi-ments." J. Ind. Hyg. Toxicol., Vol. 26, pp. 191-108, 1944.
17. Baetjer, A. M. "The Effect of Port...and Cementon the Lungs with Special Reference to Sus-ceptibility to Lobar Pneumonia." J. Ind. Hyg.Toxicol., Vol. 29, pp. 250-258, 1947.
'18. Vintinner, F. J. "Effects of Aluminum Dust onSusceptibility to Lobar Pneumonia. Animal Ex-periments." Arch. Ind. Hyg., Vol. 4, pp. 217-220, 1951.
19. Amdur, M. 0. "The Respiratory -Responses ofGuinea Pigs to Sulfuric Acid Mist." Arch. Ind.Health, Vol. 18, pp. 407-414, 1958.
20. Amdur, M. 0. and Corn, M. "The Irritant Po-tency of Zinc AmMonium Sulfate of DifferentParticle Sizes." Am. Ind. Hyg. Assoc. J., Vol.24, pp. 326-333, 1963.
21. Amdur, M. 0., Silverman, L., and Drinker, P."Inhalation of Sulfuric Acid Mist by HumanSubjects." Arch. Ind. Hyg., Vol. 6, pp. 305-313,1962.
22. Amudr, M. 0. and Underhill, D. W. "The Effectof Various Aerosols on the Response of GuineaPigs to Sulfur Dioxide." Arch. Environ. Health,Vol. 16, pp. 460-468, 1968.
23. Amdur, M. 0. "The Influence of Aerosols uponthe Respiratory Response of Guinea Pigs toSulfur Dioxide." Am. Ind. Hyg. Quart., Vol.18, pp. 149-155, 1957.
24. Amdur, M. 0. "The Effect of Aerosols on theResponse to Irritant Gases." In: Inhaled Par-ticles and Vapours, Vol. I, C. N. Davies (ed.),Pergamon Press, London, pp. 281-292, 1961.
25. Amdur, M. 0. "The Response of Guinea Pigs toInhalation of Formaldehyde and Formic AcidAlone and with a Sodium Chloride Aerosol."Intern. J. Air Pollution, Vol. 3, pp. 201-220,1960.
26. Amdur, M. 0. "The Physiological Response ofGuinea Pigs to Atmospheric Pollutants." In-tern. J. Air Pollution, Vol. 1, pp. 170-183, 1959.
27. Amdur, M. 0. "The Respiratory Response ofGuinea Pigs to the Inhalation of Acetic Vapor."Am. Ind. Hyg. Assoc. J., Vol. 22, pp. 1-5, 1961.
28. Nadel, J. A., Corn, M., Zwi, S., Flesch, J., andGraf, P. "Location and Mechanism of AirwayConstriction after Inhalation of Histamine Aero-sol and. Inorganic Sulfate Aerosol." In: InhaledParticles and Vapours, Vol. II, C. N. Davies(ed.), Pergamon Press, London, pp. 55-67, 1967.
29. Dautrebande, L. "Microaerosols." AcademicPress, New York, 1962.
30. DuBois, A. D. and Dautrebande, L. "Acute Ef-fects of Breathing Inert Dust Particles and ofCarbachol Aerosol on the" Mechanical CLarac-teristics of the Lungs in Man. Changes in Re-sponse after Inhaling Sympathomimetic Aero-sols." J. Clin. Invest., Vol. 37, pp. 1746-1755,1958.
31. Amdur, M. 0. "The Effect of High Flow-Re-sistance on the Response of Guinea Pigs to Ir-ritants." Am. Ind. Hyg. Assoc. J., Vol. 25, pp.564-568, 1964.
32. McDermott, M. "Acute Respiratory Effects ofthe Inhalation of Coal Dust Particles." J. Phys-iol., Vol. 162, p. 53, 1962.
33. Amdur, M. 0. and Creasia, D. A. "The Irri-tant Potency of M-Terphenyl of Different Par-ticle Sizes." Am. Ind. Hyg. Assoc. J., Vol. 27,pp. 349-352, 1966.
34. Tremer, H., Falk, H. L, and Kotin, P. "Effectof Air Pollutants on Ciliated Mucus-SecretingEpithelium." J. Natl. Cancer Inst., Vol. 23, pp.979-997, 1959.
35. Stockinger, H. E. "Toxicologic Perspective inPlanning Air Pollution Studies." Am. J. PublicHealth, Vol. 13, pp. 742-751, 1953.
36. Vorwald, A. J. "Effect of Inert Dusts in AirPollution." In: U.S. Technical Conference onAir Pollution, McGraw-Hill, New York, 1952,pp. 485-488.
37. Schrenk, H. H. "Causes, Constituents and Physi-cal Effects of Smog Involved in Specific Dra-matic Effects." Arch. In Hyg., Vol. 1, pp.189-194, 1950.
38. Dautrebande, L. "Bases experimentales de laprotection contre les gas de combat." J. Ducu!lot (Belgium), 1939.
39. Dautrebande, L. and Capps, R. "Studies onAerosols. IX. Enhancement of Irritating Effectsof Various Substances in the Eye, Nose, andThroat by Particulate Matter and Liquid Aero-sols in Connection with Pollution of the Atmo-sphere." Arch. Intern. Pharmacodyn., Vol. 82,505-527, 1950.
40. Dautrebande, L., Shaver, J., and Capps, R."Studies on Aerosols. XI. Influence of Particu-late Matter on Eye Irritation Produced by Vola-tile Irritants and Importance of Particle Sizein Connection with Atmospheric Pollution."
Arch. Intern. Pharmacodyn., Vol. 85, pp. 17-48,1951.
41. LaBelle, C. W., Long, J. E., and Christofano,E. E. "Synergistic Effects of Aerosols. Particu-lates as Carriers of Toxic Vapors." Arch. Ind.Health, Vol. 11, pp. 297-304, 1955.
42. Dalhamn, T. and Reid, L. "Ciliary Activity andHistologic Observations in the Trachea afterExposure to Ammonia and Carbon Particles."In: Inhaled Particles and Vapours, Vol. II, C.N. Davies (ed.), Pergamon, London, 1967, pp.299-306.
43. Boren, H. C. "Carbon as a Carrier Mechanismfor Irritant Gases." Arch. Environ. Health,Vol. 8, pp. 119-124, 1964.
44. Gross, P., Rinehart, W. E., and DeTreville, R. T."The Pulmonary Reactions to Toxic Gases."Am. Ind. Hyg. Assoc. J., Vol. 27, pp. 315-321,1967.
45. Johnstone, H. F. and Coughanowr, D. R. "Ab-sorption of Sulfur Dioxide from Air Oxida-tion in Drops Containing Dissolved Catalysts."Ind. Eng. Chem., Vol. 50, pp. 1169-1172, 1958.
46. Johnstone, J. F. and Moll, A. J. "Formation ofSulfuric Acid in Fogs from Sulfur Dioxide inAir Containing Nuclei of Manganese and IronSalts." Preprint. (Presented at the 136th Amer-ican Chemical Society meeting, Atlantic City,New Jersey, 1959.)
47. Pascua, M. "Increased Mortality from Cancerof Respiratory System." Bull. World HealthOrgan., Vol. 12, pp. 687. 704, 1955.
48. Kotin, P. and Falk, H. L. "The Role and Actionof Environmental Agents in the Pathogenesisof Lung Cancer: I. Air Pollutants." Cancer,Vol. 12, pp. 147-163, 1959.
49. Kotin, P. "The Role of Atmospheric Pollutionin the Pathogenesis of Pulmonary Cancer. AReview." Cancer Res., Vol. 16, pp. 375-393, 1956.
50. Cambell, J. A. "Cancer of the Skin and In-crease in Incidence of Primary Tumors of Lungin Mice Exposed to Dust Obtained from TarredRoads." Brit. J. Exptl. Pathol., Vol. 15, pp. 287-294, 1934.
51. Clemo, G. R., Miller, E. C., and Pybus, F. C."The Carcinogenic Action of City Smoke." Brit.J. Cancer, Vol. 9, pp. 137-141, 1955.
52. Kotin, P. and Falk, H. L. "Experimental In-duction of Pulmonary Tumors in Strain A MiceFollowing Their Exposure to an Atmosphere ofOzonized Gasoline." Cancer, Vol. 9, pp. 910-917,1956.
53. Kotin, P. and Wiseley, D. V. "Production ofLung Cancer in Mice by Inhalation Exposureto Influenza Virus and Aerosols of Hydrocar-bons." Progr. Exptl. Tumor Res., Vol. 3, pp.186-215, 1963.
51 143
54. Hueper, W. C. "A Quest into EnvironmentalCauses of Cancer of the Lung." U.S. Dept. ofHealth, Education, and Welfare, Public HealthService, Public Health Monograph 36, 1956.
55. Lynch, J. R. and Ayer, H. E. "Measurement ofAsbestos Exposure." J. Occupat. Med., Vol. 10,pp. 21-24, 1968..
56. Balzer, J. L. "Industrial Hygiene for Indus-trial Workers." J. Occupat. Med., Vol. 10, pp.25-31, 1968.
57. Tabershaw, I. R. "Asbestos 'as an Environmen-tal Hazard." J. Occupat. Med., Vol. 10, pp.32-37, 1968:
58. Cralley, L. J., Cooper, W. C., Lainhart, W. S.,and Brown, M. C. "Research on Health Effectsof Asbestos." J. Occupat. Med., Vol. 10, pp. 38-41, 1968.
59. Cralley, L. J., Keenan, R. G., Lynch, J. R., andLainhart, W. S. "Source and Identification ofRespirable Fibers." Am. Ind. Hyg. Assoc. J.,Vol. 29, pp. 129-135, 1968.
60. Cralley, L. J., Keenan, R. G., Kuepel, R. E., andLynch, J. R. "Characterization and Solubilityof Metals Associated with Asbestos Fibers."Am. Ind Hyg. Assoc. J., Vol. 29, p. 125, 1968.
61. Sawicki, E Elbert, W. C., Hauser, T. R., Fox,F. T., and Stanley, T. W. "Benzo(a)pyrene Con-tent of the Air of American Commu'.; ties." Ind.Hyg. J., Vol. 21, pp. 443-451, 1960.
62. Hueber, W. C., Kotin, P., Tabor, E. C., Payne,W. W., Falk, H., and Sawicki, E. "CarcinogenicBioassays of Air Pollutants." A.M.A. Arch.of Pathology, Vol. 74, pp. 89-115, 1962.
63. Falk, H. L., Markul, I., and Kotin, P. "Aro-matic Hydrocarbons. IV. Their Fate FollowingEmission into the Atmosphere and Exposure toWashed Air and Synthetic Smog." A.M.A. Arch.Ind. Health, Vol. 13, pp. 13-17, 1956.
64. Falk, H. L., Miller, A., and Kotin, P. "Elutionof 3, 4-Benzopyrene and Related Hydrocarbonsfrom Soots by Plasma Proteins." Science, Vol.127, pp. 474-475, 1958.
65. Falk, H. L. and Steiner, P. E. "The Identifica-tion of Aromatic Polycyclic Hydrocarbons inCarbon Blacks." Cancer Res, Vol. 12, pp. 30-39,1952.
66. Pylev, L. N. "Experimental Production of Pul-monary Cancer in Rats by Intratracheal Intro-duction of 9, 10- dimethyl -1, 2-Benzanthracene."Biull. Eksp. Biol. Med., Vol. 52, pp. 99-102, 1961.(In Russian)
67. Greezuitay, L. A. "On the Mechanism of Blast-
omogenic Action of Urethane." Vopr. Onkol.,Vol. 2, pp. 671-678, 1956. (In Russian)
68. Saffiotti, U., Cefis, F., Kolb, L. H., and Grote,M. J. "Intratracheal Injections of ParticulateCarcinogens into Hamster Lungs." Proc. Am.Assoc. Cancer Res., Vol. 4, p. 59, 1963.
69. Saffiotti, U., Cefis, F., and Kolb, L. H. "Broncho-genic Carcinoma Induction by Particulate Car-cinogens." Proc. Am. Assoc. Cancer Res., Vol.5, p. 55, 1964.
70. Saffiotti, U., Cefis, F., Kolb, L. H., and Shubik,P. "Experimental Studies of the Conditions ofExposure to Carcinogens for Lung Cancer In-duction." J. Air Pollution Control Assoc., Vol.15, pp. 23-25, 1965.
71. Shabad, L. M., Pylev, L. N., and Kolesnichenko,T. S. "Importance of the Deposition of Carci-nogens for Cancer Induction in Lung Tissue."J. Natl. Cancer Inst., Vol. 33, pp. 135-141, 1964.
72. Faulds, J. S. "Carcinoma of the Lung in Hema-tite Miners." J. Pathol. Bacteriol., Vol. 72, pp.353-366, 1956.
73. Bonser, G. M., Faulds, J. S., and Stewart, M. J."Occupational Cancer of the Urinary Bladderin Dyestuffs Operatives and of the Lung inAsbestos Textile Workers and Iron-Ore Miners."Am. J. Clin. Pathol., Vol. 25, pp. 126-134, 1955.
74. Haddow, A. and Horning, E. S. "On the Car-cinogenicity of an Irondextran Complex." J.Natl. Cancer Inst., Vol. 24, pp. 109-147, ,1960.
75. Epstein, S. S., Joshi, S., Andrea, J., Mantel, N.,Sawicki, E., Stanley, T., and Tabor, E. C. "TheCarcinogenicity of Organic Particulate Pollut-ants in Urban Air after Administration of TraceQuantities to Neonatal Mice." Nature, Vol. 212,pp. 1305-1307, 1966.
76. Kuschner, M. "The J. Burns Amberson Lecture :The Causes of Lung Cancer." Am. Rev. Res-pirat. Diseases, Vol. 98, pp. 573-590, 1968.
77. Auerbach, 0., Stout, A. P., Hammond, E. C., andBarfinkel, L. "Smoking Habits and Age in Re-lation to Pulmonary Changes. Rupture of Al-veolar Septums, Fibrosis, and Thickening ofWalls of Small Arteries and Arterioles." NewEngl. J. Med., Vol. 269, pp. 1045-1054, 1963.
78. Carnes, W. H. "The Respiratory Epithelium inRelation to Selected Diseases and Environmen-tal Factors." (Report to the U.S. Dept. ofHealth; Education, and Welfare) April 1964.
79. Kotin, P. and Falk, H. L. "Carcinogenesis of theLung: Environmental and Host Factors." In:The Lung. Williams and Wilkins Co., Balti-more, Maryland, pp. 203-225, 1968.
Chapter 11
EPIDEMIOLOGICAL APPRAISAL OFPARTICULATE MATTER
Table of ContentsPage
A. INTRODUCTION 148
B. APPLICATION OF EPIDEMIOLOGY TO AIR POLLUTION 1481. Indices 1482. Cautions 148
C. INDICES OF HUMAN RESPONSE: THE EPIDEMIOLOGICSTUDIES 1501. Acute Episodes 150
a. Mortality 150b. Morbidity 154
2. Chronic (Long-Term) Air Pollution 156a. Day-to-Day Variations in Mortality and Morbidity 156b. Geographical Variation in Mortality 156
1. Studies Based on Available Data 1562. Special Studies Involving the Collection of New Data 158
c. Geographic Variations in MorbiditySpecial Studies 161d. MorbidityIncapacity for Work 164
3. Studies of Children 1654. Studies of Pulmonary Function 1675. Studies of Panels of Bronchitic Patients 168
D. SUMMARY 169
E. REFERENCES. -176
List of FiguresFigure11-1 Mortality Figures for the January 1956 and December 1957 Smog
"Episodes" in London 15111-2 Mortality and Air Pollution in Greater London during the Winter of
1958-1959 15211-3 Death Rates and Air Pollution Levels in Dublin, Ireland, for 1938-
1949
11-4 Average Annual Death Rate from all Causes 160
11-5 Average Annual Death Rate from Asthma, Bronchitis, or Emphy-sema Indicated on the Death Certificate
11-6 Average Annual Death Rate from Gastric Cancer 161
11-7 Age-Standardized Morbidity Rate per 1,000 for Three Diseases .inJapan 162
11-8 Effect on Bronchitis Patients of High Pollution Levels (January1954)
155
160
146Y
154
169
List of TablesTable _ Pope11-1 Pollution Levels in Salford (seasonal daily averages) 15911-2 Average Annual Death Rates Per 1,000 Population From All Causes
According to Economic and Particluate Levels, and Age: WhiteMales 50-69. Years of Age, Buffalo and Environs, 1959-1961 159
11-3 Average Annual Death Rates Per 100,000 Population from ChronicRespiratory Disease According to Economic and Particulate Levels,and Age: White Males 50-69 Years, Buffalo and Environs, 1959-1961 160
11-4 Average Annual Death Rates Per 100,000 Population for GastricCancer According to Economic and Particulate Levels: White Males50-69 Years of Age, Buffalo and Environs, 1959-1961 161
11-5 Response of Telephone Workers in the U.K. and the U.S.A. to AirPollution 163
11-6 Summary Table of Epidemiological Studies 171
.155t
I e 147
Chapter 11
EPIDEMIOLOGICAL APPRAISAL OF PARTICULATE MATTER
A. INTRODUCTION
Health effects produced by atmosphericparticulate matter are discussed in this chap-ter in terms of epidemiologic studies. Be-cause particulate matter tends to occur inthe same kinds of polluted atmosphere assulfur oxides, few epidemiologic studies havebeen able adequately to differentiate the ef-fects of two pollutants. It follows, therefore,that the studies presented in this chapter arefrequently identical with those described inthe companion document, Air Quality Cri-teria for Sulfur Oxides.
Epidemiologic studies, as distinguishedfrom toxicologic or experimental studies,analyze the effects of pollution from ambi-ent exposure on groups of people living ina community. Such studies have the advan-tage of examining illness where it occursnaturally, rather than in a laboratory, butcarry the disadvantage of not being able tocontrol precisely all the factors of possibleimportance. Nevertheless, the preparationof air quality criteria must rest on epidemio-logic studies because of the very severe limi-tations of toxicologic and industrial studiesfor this purpose. Other countries, notablythe Netherlands and Sweden, have basedtheir air quality criteria solely on epidemio-logic studies.
In determining whether or not an asso-ciation is causal, consideration must be givento several aspects of association which in-clude strength, consistency, specificity, tem-porality, biological gradient, plausibility, co-herence, and analogy.' A judgment of thevalue of an epidemiologic study requires anunderstanding of these aspects. Many typesof epidemiologic evidence suggest that airpollution may exert considerable influence onhealth, as well as on the "satisfaction with
:148
life," of major segments of the world popu-lation.
Several health indices are described inSection B-1; certain precautions whichshould be observed in the application of epi-demiologic methods to air quality criteriaare suggested in Section B-2. The studiesthemselves are listed in Section C, accord-ing to the index employed.
B. APPLICATION OF EPIDEMIOLOGYTO AIR POLLUTION STUDIES
1. Indices'Various indices of health may be used for
correlation with air pollution by the oxidesof sulfur. Among the possible indices are:
1. mortality (greater than expected)(i) deaths from all causes(ii) deaths from specific causes(iii) deaths among the different age
and sex groups2. morbidity
(i) incidence of diseasechronicbronchitis, pulmonary emphy-sema, diffuse interstitial pneu-monitis, cancer of respiratorytract, disease of remote organ(e.g., gastrointestinal, ophthal-mic, and cardiovascular sys-tems)
(ii) prevalence of diseasessameexamples as for "incidence"
(iii) prevalence of respiratory symp-toms (e.g., changes in qualityand/or quantity of sputumproduction)
(iv) exacerbation of diseasesrhi-norrhea, asthma, tracheobron-chitis, and chronic illness, and
.,156
enhancement of infection: pne-umonia, sinusitis, otitis, mas-toiditis
(v) changes in clinical conditions(e.g., bronchitic patients)
3. changes in various aspects of lungfunction(i) ventilatory functiondecrease
in peak flow rate, decrease inspirometric volumes, impair-ment of flow-volume relation-ship, and increased airway re-sistance
(ii) blood/gas distributionimpair-ment of lung-gas distribution
(iii) blood/gas exchangeimpair-ment of pulmonary blood-gasexchange
(iv) increased work of breathingDefinitions of the various disease states are
to be found in the glossary; most of the pul-monary function methods have been men-tioned in Chapters 9 and 10..
The manner of presentation of the state ofepidemiological knowledge of effects of par-ticulate matter in the ambient atmospherewhen accompanied by the oxides of sulfur isoutlined in the Table of Contents.
2. Cautions
In the first place, as discussed in Chapter1, methods of measurement vary from coun-try to country and place to place. Resultsfrom the high volume sampler and the resultsfrom smoke stain calibration are very dissimilar. Also, coh values cannot be comparedwith µg /m'.
Secondly, particle size plays an importantpart in the appropriateness of the measuringtechnique as it does in determining the siteand effectiveness of deposition in the respirsetory tract. (See Chapter 9.) However, sizedistribution of particles has nearly alwaysbeen ignored in field studies.
Thirdly, pollution and health indices arenot always measured over the same timeperiods. It is to be hoped that the pollutionlevels cited bear some relation to those extantduring the time when the chronic diseasestates were developing. Further, acute effectsrequire frequent short-term pollution mess-
urements to enhance detection, while long-term chronic processes may be adequatelyrelated to long-term sampling intervals. Airpollution measurements useful in studies ofacute health effects are becoming available;a less satisfactory situation exists for thelong-term effects studied.
In many instances the possible role of cig-arette smoking has not been considered. It isexpected that future epidemiologic studiesinvolving adults will routinely collect data onsmoking habits of the study group. Otherfactors are significantly related to respira-tory disease. These include occupational andother past exposures; infections, past andpresent; and allergy and heredity.
Few or no epidemiologic studies have beenpossible where the pollution challenge hasbeen limited to particulate matter, unaccom-panied by significant amounts of other pol-lutant substances. Indeed, most of the availa-ble conclusions link particulate levels withthose of concurrently measured sulfur di-oxide; some studies attempt statistical sep-aration of the culpability of one factor fromthe other in the effects cited.
In seeking the possible effects on popula-tions resident in areas of differing air pollu-tion, factors such as smoking, type and condi-tions of employment, ethnic group, and mobil-ity in response to experienced irritation ordisease have sometimes been considered..There has, however, been a minimum of at-tention paid to the indoor or domestic envi-ronments and their potential contribution.Measurement of such indoor exposures mightbe difficult, but omission of the informationcould well modify the appraisal of the im-portance of particulate pollution.
Toxicologic studies indicate a specific po-tential of some particulate materials to pro-duce human responses. The levels used intoxicologic studies are far higher than thosefound in the communities in the epidemio-logic studies under review. Thus the actualresponsibility of "particulate matter" forthe community responses is uncertain, andit is sometimes necessary to invoke addition-al concepts; for example, the idea of syn-ergism with other known or unkown ambientpollutants, or the idea that particulate matteris but an index of availability of some other
149
substance (s) which are fully responsible forthe effects reported.
Over a short period of time, mortalityfluctuates considerably, and only a syste-matic, long-term approach will allow a validdetermination of the real role of air pollution.Cassell et al.2 have reviewed the problem ofdetecting peaks in mortality and relatingthem to any single variable. The danger withepisodic studies is that short-term fluctuationin the death rate, when picked to coincidewith an air pollution incident, may appearto be causally related; in the long term, how-ever, numerous other unassociated peaks arefound in both the death rates and the air pol-lution levels.
Specific substances encountered as respira-ble particles, and associated with disease en-tities (beryllium, asbestos, arsenic, vanadi-um, lead, airborne pathogens, etc.) are notassessed in this report. They deserve consid-eration, however, as exemplars of the modesof response of which the human is capable,and which may delay or confound the recog-nition of the importance of "particulate mat-ter" inhalation. The demonstration of theimportance of aerodyriamic behavior ratherthan of mass or particle dimension for bothimpingement and retention of asbestos isstriking. Long-delayed effects from relativelybrief community dispersion exposures to as-bestos and beryllium are significant (seeChapter 10). Furthermore, penetration of"poorly cleared" particles of asbestos to re-mote body sites suggests complex body trans-port mechanisms, differing organ or. tissuesensitivities, and the need for evaluation ofas yet untested relationships between diseaseentities and respirable offenders. These mod-els confer some sense of urgency to establish-ing the relationships of human disease anddysfunction to air pollution by "general par-ticulate matter."
The concept of "susceptible population"demands consideration. Human responses totoxicants, and to community air pollution,show wide variations, which contribute in nosmall way to the difficulty in assessing in ageneral manner the effects of pollutants.Since air quality criteria must, unless other-wise specified, consider "all" population rath-er than just major segments of it, studies
150
must consider especially the impact of airpollution on the "most sensitive" responders.Many factors seem to enhance susceptibilityor sensitivity to air pollution. These includebeing at the extremes of age (i.e., infants andthe very old) ; having pre-existing chronicrespiratory disease (e.g., pulmonary emphy-sema or chronic bronchitis); having pre-existing cardiovascular disease (functionalcapacity not defined) ; regularly smoking cig-arettes; or living in overcrowded or depressedsocioeconomic strata. Some of these factorshave been singled out for attention in thereferences to be cited, and the level of pol-lutant said to have an "effect" may take cog-nizance of such special sensitivity.
The effects discussed are related insofar aspossible to specific pollution over specific timeintervals; it must be emphasized that lowervalues by no means imply a "no effect" levelof the pollutants.
C. INDICES OF HUMAN RESPONSE:THE EPIDEMIOLOGIC STUDIES
1. Acute Episodesa. Mortality
In conurbations, such as London, NewYork, Chicago, and Detroit, it has been pos-sible to observe deviations from the movingaverages of deaths during various seasons,and to relate such deviations to the coincidentperiod levels of air pollutants.,
In writing about the Mease Valley episodein 1936, Firket stated that if there were asimilar phenomenon in London, some 3,200death might occur 1.3 Unfortunately, he wasquite accurate iri his estimate since, in Decem-ber 1952, the world's most disastrous smogincident occurred in London, causing about4,000 excess, deaths throughout the GreaterLondon area. Marked increases were notedin both respiratory and cardiovascular deaths(and for almost every cause except trafficaccidents; presumably the smog was too thickfor people to drive). Since some of the diseas-es such as lung cancer and tuberculosis wereobviously existent before the pollution ep-isode, much of the effect of the fog was clear-ly to hasten the death of people who werealready ill. Detailed investigations were madeof 1,280 post-mortem reports of persons who
-158
had died before, during, or shortly after theepisode. No fatalities were found which couldnot have been explained by previous respira-tory or cardiovascular lesions. In this episodeas in others, the elderly and persons with pre-existing pulmonary and cardiac disease weremost susceptible.
A number of investigations have analyzedand compared the various London episodes.The report by Brasser et al.° appears to coverall the episodes and to present a detailedanalysis of each of these episodes, pointingout the importance of the duration of themaximum values. More recently, Joostinghas examined the relationship between theduration of maximum values of sulfur dioxideand smoke during air pollution episodes, as
JANUARY, 1956
DEC. JAN.
well as the differential relationship betweensulfur dioxide and smoke levels and the re-sulting mortality.
Gore and Shaddick s and Burgess andShaddick reviewed acute "fog" episodeswhich occurred in London in 1954, 1955, 1956(January and Decmeber) , and 1957 (Decem-ber), in terms of excess mortality above amoving average, related to the mean of dailyreadings at seven stations for smoke and SO2.Figure 11-1 shows mortality figures for theJanuary 1956 and December 1957 episodes.Somewhat differing patterns of onset ofmortality rise, of age of population sufferingmost heavily, of deaths related to bronchitisand to other respiratory diseases, and of totaldeaths, were noted in these acute episodes.
ALL AGES
70+ YEARS
0 69 YEARS
DECEMBER. 1957
25 30 5 10 15
NOV. DEC.
FUMES 11-1. Mortality Figures for the January 1966 and December 1967 Smog "Episodes" in London .° (Thefigure shows the increase in numbers of deaths during sjn g, episodes" (shaded periods),' especially in theolder age group.)
347.335 P.0.3 69.461 REV. REPRO .
151
Common to them, however, were elevationsin the mean daily levels of SO2 and smoke,measured at seven different stations, fromtwo to four times the winter average levels;"effects" were estimated at 2,000 pg/m3 blacksuspended matter together with 0.4 ppm(1,145 pg /me) SO2 (representing all acidicgases). Deaths ascribed to bronchitis werematerially affected, but deaths due to othercauses also increased. Deaths appeared tobegin to increase before the onset of the ep-isodes; during the episodes, of course, theyincreased substantially. Scott 10 observed asimilar relationship, for similar periods of"fog," with "effective pollutant" levels atseven different stations in London of 2,000pg/m3 for smoke and 0.4 ppm for SO2. Therewas a sharp impact on the elderly and thegreatest proportionate rise, for cause ofdeath, in bronchitic.s.
Martin and Bradley 11 correlated dailymortality (all causes) and daily bronchitismortality with mean daily black suSpendedmatter (see Figure 11-2) measured at sevenlocations in London for the winter of 1958-1959, and also found a significant positive as-
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sociation between mean daily sufur dioxidelevels and deaths (all causes). Bronchitisdeaths showed a lower correlation with thepollution level, and the authors suggest theneed for consideration of effects of air pol-lution on patients with cardiovascular di-sease. In addition, excess deaths have beenrelated to increases (on the day precedingdeath) of mean daily black suspended matterby more than 200 pg/m3, and rises in meandaily SO2 of more than about 75 pg/m3 (2.5pphm). In a later paper," data are shown tosuggest an increase in mortality from allcauses, and of respiratory and cardiac mor-bidity, associated with levels of smoke about1,000 pg/m3, and SO2 concentrations of 715pg/m3 (25 pphm). This "effect" is properlyrelated to abrupt rises in the concentration ofsmoke and/or S02, with perhaps a continuumof effects at lower levels. Since these meas-urements were obtained at a single point inCentral London, it should be presumed that arelatively wide range of values around theselevels actually contributed to the mortalitystatistics which were correlated. A reanalysisby Lawther 13 of these mortality studies
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(LOGI° OF BLACK SUSPENDED MATTER CONCENTRATION)
FIGURE 11-2. Mortality and Air Pollution in Greater London during the Winter of 1958-1959." (The figureshows increased mortality due to "all causes"! ,nd to bronchitis during a period of high pollution.)
1.160152
places the mortality "effect" at about 750 pg/m3 for smoke and about 715 µg /me (0.25ppm) for SO2. hosting states that the maxi-mum sulfur dioxide concentration abovewhich significant correlation occurs withdeath and disease is 400 µg/m3 to 500 µg /m'(0.15 ppm to 0.19. pppm)* when there is ahigh soot content.
The Dutch report on sulfur dioxide,° whichdiscusses in detail seven air pollution episodesin London, states that in the December 1956episode, 400 excess deaths, or 25, percentabove expected, were observed in GreaterLondon at maximum 24-hour levels of 1,200pg/m8 for smoke and 1,100 pg/m3 (0.41ppm) * for SO2. The report also notes that inJanuary 1959, 200 excess deaths were observ-ed in Greater London, or 10 percent aboveexpected mortality, at a level of 1,200µg /m' for smoke and 800 µg /m' (0.30 ppm) *for SO2. The episodes all took place duringwinter; cold weather seems to have been animportant feature of London air pollutionmortality.
In Martin's review 12 in 1964 of daily mor-tality in London during the winters of 1958-1959 and 1959-1960, he concluded: "Fromthe data it would be difficult to fix any thresh-old value below which levels of air pollutionmight be regarded as safe." However, hisreview included data with smoke concentra-tions ranging upward from 500 lAg/m3and ac-companied by sulfur dioxide concentrationsof about 400 µg /m' (0.14 ppm) and above.
As a result of smoke control regulations,the particle content of London air has steadi-ly decreased since the 1950's, but the sulfurdioxide concentrations have not decreasedproportionately. At the same measuring sitesas in 1952, sulfur dioxide was actually slight-ly higher in the 1962 episode than in that of1952, buC smoke levels were considerablylower. Also, as Brasser et at.° have notedthere was only one day of maximum pollutionvalues in 1962 as contrasted with the 2 daysof maximum pollution in December 1952.Although the smoke levels appear to be bet-
*SO, is converted from ppm to pg/m8 in the Dutchreport by using the equivalency 2,700 pg/ne.-1 ppm;Scott apparently used 2,860 pg/nei1 ppm; this re-port uses 2,860 pg/m8.-.1 ppm.
ter related to the amount of excess mortality,other factors must be considered as possiblyalso reducing the number of deaths. Since1952, a great deal of publicity has been givento the harmful effects of smog, and more sus-ceptible individuals have been encouraged touse masks and filters and stay indoors. Inaddition, when episodes come close together,a large number of susceptible individualsmight not accumulate, since some are killedoff each time. An effect as large as that seenin the first incident would not, therefore, beexpected.
The number of deaths in New York Citywas reviewed for excess mortality in rela-tion to the air pollution episode of November1953, by Greenburg et al." Excess deathswere related to elevations of concentrationsof sulfur dioxide and suspended particles.Average daily suspended particulate mattermeasured in Central Park was in excess of5.0 coh units, while the SO2 rose from theNew York City average ranges of 430 µg /m3to 570 µg /m' (0.15 ppm to 0.20 ppm) to amaximum level of 2,460 µg /ml (0.86 ppm).For this episode, there was a "lag effect,"and distribution of excess deaths among allage groups was noted. The number of deaths,although not showing the marked rise seenin some of the London episodes, was aboveaverage for comparable periods in otheryears during and immediately after the in-cident. For the November 15 to 24, 1953,period, the average number of deaths perday was 244, whereas during the three yearspreceding and following 1953, the averagewas 224 deaths per day for the same calen-dar period.
A later episode (1962) was studied," ButGreenburg et al. did not discern an excessmortality. However, McCarron and Brad-ley," reviewing episodes in New York Cityin November and December of 1962, Januaryand February of 1963, and February andMarch of 1964, compared 24-hour averagelevels of various pollutants with New YorkCity mortality figures, employing daily de-viations from a 15-day moving average; themeasurements were performed at a singlestation in lower Manhattan and fluctuationsin the values at this station were known. tocorrelate well with those at another station
4
158
6.5 miles away. Excess deaths on December1, 1962, followed a daily average SO2 concen-tration of 2,060 µg /m° (0.72 ppm) and smokeshade in excess of 6 coh units, during a pe-riod of atmospheric inversion and low-ground-wind speed. The increased deathrates were shared by the 45-to-64 age group,as well as by the age group over 65. In alater episode (January 7, 1963) associatedwith an SO2 concentration of 1,715 µg /m'(0.6 ppm) and smoke shade at 6 coh units,there was a peak of death rate apparentlysuperimposed upon an elevated death rateaverage due to the presence of influenza vi-rus in the community. Two further episodes 'a. '7 also suggest the relationship ofexcess deaths to abrupt rises in both SO2 andsuspended smoke at times of air stagnation.
An example of the inherent danger of re-lating mortality peaks to air pollution isshown by Leonard et atli in, the Dublin stud-ies. During the war and post-war years of1941 to 1947, pot was burned as the mainfuel rather than coal, and air pollution (asmeasured by particle concentrations) wasmarkedly decreased. Sulfur dioxide levelsvaried in a manner similar to those of sus-pended particulate matter. The winter peaksin death, however, were unaffected, and thusdo not seem to be related to air pollution.When coal again became available in 1948,the air pollution levels rose with no appar-ent effect on the death rate (see Figure 11-3) . Unfortunately, it is not possible to assessthe effects of changing medical practices andthe advent of antibiotics for use in treat-ing respiratory diseases on these data.
In Detroit '° a rise in infant mortality anddeaths in cancer patients occurring over a3-day period accompanied a rise in the 3-day mean suspended particulate matter forthe same period above 200 µg /m' accom-panied by an SO2 maximum of 2,860 pgjma(1.0 ppm) (September 1952). This is notbelieved to be related to the cold temper-atures which have characterized the Londonepisodes.
In Osaka, Japan, Watanabe 2° reported onexcess deaths in a December 1962 smog epi-sode. There were 60 excess deaths relatedto mean daily concentrations of suspendedmatter greater than 1,000 pg/m3, with ac-
companying. SO2 greater than 285 µg /m'(0.1 ppm) ; the measurements were made ata single station in the central commercialarea of the city. -
When a marked increase in air pollutionis associated with a sudden dramatic rise inthe death rate or illness rate lasting for, afew days and both return to normal shortlythereafter, a causal relationship is stronglysuggested. Sudden changes in weather, how-ever, which may have caused the air pollu-tion incident, must be considered as anotherpossible cause of the death rate increase.Over the years, a number of such acute epi-sodes have been reported, and there seemslittle doubt that air pollution was the cause.
The British studies presented in this sec-, tion suggest that excess mortality, a smallrise in the daily death rate, is detectable inlarge populations if the concentrations ofsmoke and SO2 rise abruptly to levels above750 µg /m3 and 715 µg /m, (about 0.25 ppm)respectively; the same effects are noted inAmerican cities for SO2 concentrations above1,700 µg /m' (about 0.6 ppm) and a "smokeshade" of 6 coh units. The major targets arethe aged population, patients with chronic ob-structive pulmonary disease, and patientswith cardiac disease. A more distinct risein deaths is noted generally when particulatematter reaches about 1,200 pigim3 for oneday and sulfur dioxide levels exceed 1,000µg/m, (about 0.35 ppm). Daily concentra-tions of suspended particulates exceeding2,000 pg/m3 for one day in conjunction withlevels of sulfur dioxide in excess of 1,500µg /m' ( ppm) appear to be associatedwith an increase in the death rate of 20 per-cent or more over baseline levels.b. Morbidity
The acute episodes have- resulted in sub-stantial increases in illness. Thus a sur-vey in of emergency clinics at major NewYork City hospitals in November 1953 indi-cated a rise in visits for upper respiratoryinfections and cardiac diseases in both chil-dren and adults in all of the four hospitalsstudied. "Smoke shade" was close to 3 cohunits, and sulfur dioxide concentrations hadnot yet exceeded 715 µg /ms. (0.25 ppm) whenhospital admissions clearly rose."
Again, the number of emergency clinic
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visits for bronchitis and asthma at sevenlarge New York City hospitals was examinedduring the Thanksgiving 1966 air pollutionepisode.22 There was a rise in the numberof such visits on the third' day of the epi-sode, among patients age 45 and over, atthree of the seven hospitals investigated. Un-fortunately, the Thanksgiving holiday great-ly complicated evaluation of the emergencyclinic visits over the holiday period."
In the investigation of the London episodeof December 1952, information on illnesswas collected from as many sources as pos-sible including sickness claims, applicationsfor hospital admission, pneumonia notifica-tions and records of physicians. The analy-sis demonstrated a real and important in-crease in morbidity, though there was someindication that the increase in illness wasnot as large proportionately as the increasein deaths and the effects were not so suddenin producing a marked_rise in the early daysof the episode. In a number of other severeLondon episodes the increase in morbidityput a considerable strain on the health serv-ices.
These episodes reflect results which fallinto Level IV of the World Health Organiza-tion's "guides to air quality." 23 These"guides," equivalent in usage to our term."criteria," cover sets of concentrations andexposure times at which specified types ofeffects are noted or at which no effect isnoted. Level IV includes "concentrations andexposure times at and above which there islikely to be acute illness or death in sus-ceptible groups of the population."
2. Chronic (LongTerin) Air PollutionKurland 24 has called to our attention that
air pollution episodes repreient, by defini-tion, massive, overwhelming, and unusual ex-posure, and thus the most significant patho-logic effects. There is an "iceberg" effectin that such data represent the obvious, whilethe greater share of the problem remainssubmerged. We are dealing with an essen-tial dose-response situation, the upper limitsof which are represented by these episodes.a. Day-to-Day Variations in Mortality and
MorbidityIn a systematic approach to analyzinglp
156
piratory and cardiac morbidity daily in Lon-don, Martin 12 examined deiriations in mor-bidity from a 15-day moving average in Lon-don during the winters of 1958-1959 and1959-1960. Both smoke and sulfur dioxideconcentrations appear to be about equallyrelated to morbidity rates, and a definite ex-cess in morbidity seemed to exist as it did formortality,. though there was a somewhatgreater degree of irregularity.
An approach similar to Martin's, but limit-ed to observations on mortality, was used byMcCarroll and Bradley 16 in New York City.Covering a 3-year period (1962-1964) theyexamined a number of peaks in New YorkCity mortality associated with periods ofhigh air pollution. There are examples givenwhere sulfur dioxide and smoke shade ap-pear to be related to mortality. The authorspresent other episodes, however, where therelationship to air pollution is not nearly asclear, although the death rate* fluctuates toeven higher peaks. Reference to this analy-sis has already been made in.our discussionof the data on episodes in Section B.1.
McCarroll et al.22 studied residents of .aNew York City housing project, using week-ly questionnaires. Exact levels of air pol-lutants which could be used for establish-ment of air quality criteria were not given;however, the data indicate that sulfur diox-ide rather than particulate matter was asso-ciated with eye irritation. Syinptoms ofcough were also shown to be related to airpollution but were not well differentiated be-tween association with particles and sulfurdioxide. The particular time-series analysisused with these data is not well known, andthe biases inherent in its use have not beenfully determined.
b. Geographical Variations in Mortality1. Studies Based on Available Data.
Mortality and morbidity statistics each haveadvantages as well as disadvantages. Rec-ords of illness should be more fruitful in de-fining subtle effects, since illness precedesdeath and since all illness does not resultin death. Mortality statistics are collectedin every country and are available for quicktabulation. Unfortunately, the quality of
4mortality statistics varies. One of the prob-
lems is that with the present system of tabu-lating mortality data, a single cause of deathmust be selected and coded,even. thoughmore than one cause may be involved in thedeath. The single cause of death designated(e.g., specific chronic respiratory disease)depends largely on the judgment of the at-tending physician and has little, if any, rela-tion to epidemiologic use. While contributingcauses of death appear on the death cer-tificate, they are not reflected in summarytabulations. The coding of only the "under -.lying" cause of death minimizes the impor-tance of such diseases as emphysema whichoften appear on the death certificate as con-tributory or associated causes of death.25
Almost all studies of the effects of long-term exposure on death rates compare therate in one area with that in another. Mor-tality as well as morbidity studies are ham-pered by the possibility of differences otherthan air pollution existing between the areas,such as social class, occupation, age, and sexcomposition of the population, and cigarettesmoking. Assuming that almost all deathsare recorded and tabulated, comparison oftotal mortality rates (i.e., deaths from allcauses) obviates the bias of diagnostic selec-tion, but does not lessen the chances of otherassociated factors having caused the differ-ence.
Buck and Brown 26 reported in 1964 'therelation of standardized mortality ratios forthe 5-year period 1955-1959 to four vari-ables: daily smoke and SO2 concentrationsfor March 1962 (presumed representative ofthe study period), population density in 1961,and a social index of 1951. The studies in-volved populations in 214 areas of the UnitedKingdom (19 London boroughs, 49 countyboroughs, 70 boroughs, 61 urban districts,and 15 rural districts).
Statistical studies indicate that bronchitismortality had a significant positive associa-tion with both the smoke and the SO2 con-centrations encountered in these residentialareas, and also with social index. The stand-ardized mortality rates for lung cancer werenot, in general, significantly associated withsmoke or SO2 concentrations in the residen-tial areas. Examination of the tables givenby Buck and Brown suggests that the ex-
t
cess of bronchitis mortality occurred forclams of area where the average daily smokeand SO2 concentrations both exceeded 200pg/A13, Although smoking habits were re-viewed and were apparently uniform fromarea to area, occupational and domestic in-door environmental exposures were not con-sidered. The pollutant values selected forthe correlations do not cover the same timeperiod as the mortality figures.
A series of papers by Stocks' et at.,27-31related atmospheric pollution in urban andrural localities with mortality due to lungcancer, bronchitis, and pneumonia. Stand-ardized mortality ratios apparently refer tothe period 1950 to 1953 for bronchitis andpneumonia and to the period 1950 to 1954for lung cancer. Lung cancer mortality wasfound to be strongly correlated with smokedensity in the atmosphere for 26 areas ofnorthern England and Wales, for 45 districtsof Lancaster and Yorkshire, and for 30county boroughs. (Similar but weaker cor-relations were observed within Greater Lon-don.) Further, social differences in the popu-lations concerned only partially explain thiscorrelation. Bronchitis and pneumonia formales and bronchitis for females similarlyshowed strong correlations with smoke den-sity in the atmosphere. Cancers of the stom-ach and intestine in the county boroughswere also related significantly to smoke con-centrations, and other relationships are de-scribed for various areas of the country. Itis, however, difficult to extract specific quan-titative "effect" levels for smoke or the otherpollutants studied. Papers 30. 31 describe thestatistical elimination applied to develop sig-nificant correlations of spectographic analy-ses of 13 trace, elements with mortality rates.Reanalysis of the data by Anderson 52 con-firmed the importance of smoke levels, aswell as social and population parameters, tomortality from lung cancer; vanadium is alsoidentified as an important independent con-tributor to lung cancer, female cancer, and;,,pneumonia mortalities.
In summary, the results of this analysisof long-term mortality indicate effects whichwould coincide with Level III of the WorldHealth Organization's "guides to air qual-
23 Level III is defined as "concentrations
U1 157
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and exposure times at and above which thereis likely to be impairment of vital physiologicfunctions or changes that may lead to chronicdiseases or shortening of life."
2. Special Studies Involving the Collectionof New Data.In 1964, also, Wicken andBuck 33 reported on a study of bronchitis andlung cancer mortality in six areas of North-east England, one in Eston, another in Stock-ton and four in rural districts. The deathscovered the period 1952 to 1962. The surveyof decedents with cause of death from bron-chitis or lung cancer was matched againstthe survey of decedents with cause of deathfrom nonrespiratory disease controlled forage and sex; the basis for the diagnosticclassifications was not stated in the report.Personal interviews were carried out withnext of kin. Personal interviews of a ran-dom sample of households were also con-ducted to obtain sex, age, smoking habits andoccupation of the population at risk, the liv-ing population. The survey of decedents wascarried out between January and October1963; the survey of the living population wascarried out between December 1963 andMarch 1964.c.iSmoke and sulfur dioxide con-centrations were measured in the Eston ur-ban district. One year's aerometric data wasobtained. The study was excellent in prin-ciple though, unfortunately, sulfur dioxide.and particulate values were available onlyfor the Eston urban district.
Eston, itself, as a sub-study, was subdi-vided into North Eaton and South Eston.North Eston contains or lies near heavy in-dustrial plants, whereas South Eston is aresidential area. During the period May1963 to April 1964, mean weekly observa-tions of the sulfur dioxide and smoke con-centrations were carried out in two sites inNorth Eston and one station in South Eaton.Smoke values were 160 pg/m3 and 80 µg /mafor North and South Eston respectively. Thesulfur dioxide value in North Eston on theyearly average was' 115 pg/ma (0.040 ppm)and for South Eston it was 74 ,:g /ma (0.026ppm). The deaths studied occurred between1952 and 1962. Adjustments were made fordifferences in age composition, smoking hab-its, and social class, and these were' insuffi-cient to explain the differences in lung can-
cer and bronchitis mortality rates betweenthe two localities. Occupational exposure topollution was then taken into account in theanalysis. The conclusion was that there isan association between the degree of airpollution and the incidence of lung cancerand bronchitis mortality in the two areas ofthe Eston urban district. Though both sul-fur dioxide and smoke values and concen-trations are furnished in the report and theeffects apparently cannot be separated, Gras-ser et al.6 apparently have used the sulfurdioxide concentration as the more relevantmeasure of this study.
The community of Salford was classifiedinto three pollution areas by Burn and Pem-berton," according to Table 11-1. Five sam-pling stations in the area were employed.Despite the closeness of the ranges of values,a high rate of bronchitis mortality, of lungcancer mortality, and of deaths from allcauses, was observed in the high, comparedto the lower pollution wards. It appears (seeSection C-4) that there was also an increasedrate of bronchitis morbidity in the highlypolluted wards.
Winkelstein et al.35-37 analyzed pollutioneffects in a group of studies made in theBuffalo, New York, area. In July of 1961,21. air sampling stations were set up in andaround the city of Buffalo, and daily valuesfor suspended particulates, dustfall, and ox-ides of sulfur were taken until June of 1963.Suspended particulate levels were used asthe index of air pollution. On the basis ofthe measurements, the study area was di-vided into. four contiguous areas 'accordingto their levels of air pollution. Level 1 wasless than 80 pg /m3 (2-yr. geometric mean) ;level 2, 80 pg /me to 100 pg/m3; level 3,100 pg/ma to 135 pg/ma; and level 4, greaterthan 135 µg /me. Each area was also dividedinto five economic groupings. Mortality fig-ures for the area were taken from the period1959 to 1961, with the 1960 census provid-ing the population basis.
Annual death rates per 100,000 popula-tion for (1) all causes of death; (2) chronicrespiratory disease; (3) malignant neo-plasms of the bronchus, trachea, and lung;and (4) gastric carcinoma were related tothe four areas of air pollution intensity and
158 1 J4166
Table 11 -1. POLLUTION LEVELS IN SALFORD (SEASONAL DAILY AVERAGES)"
Pollution areaclassification
Smoke pg/mSO2 µg /m'
(ppm in parentheses)
Deathsobserved
x 100expected
Winter Summer Winter SummerAll
causes BronchitisLungcancer
High 680 270 716 266 106 128 124(0.25) (0.09)
Intermediate 490 170 460 200 100 97 84(0.16) (0.07)
Low 450 170. 340 146 90 52 79(0.12) (0.06)
Note: The data in the original report show SO: concentrations in parts per hundred million (pphm).
to the socioeconomic levels of the deceased.Among white males between 50 and 69
years of age, the death rate from all causeswas 20 per 1,000 in the area with the leastsuspended particulates (less than 80 pg/m3).It was 20 percent higher in the next mostpolluted area (between 80 pg/m3 and 100pg/m3) and twice as high in the most pol-luted area (more than 135 pg/m3). See Table11-2 and Figure 114.
Among white males between 50 and 69years of age, the death rate from chronicrespiratory disease was 42 per 100,000 popu-lation for those living in the area with theleast suspended particulates, 40 percenthigher for those living in the next mostpolluted area, and about three times as highfor those living in the most polluted area.See Table 11-3 and Figure 11-5. Suspendedparticulate levels did not appear related todeaths from cancer of the bronchus, trachea,or lung. However, positive correlations were
established with suspended particulate levelsand total mortality, and mortality fromchronic respiratory disease, regardless ofthe economic level of the deceased. More-over, a positive correlation was establishedbetween suspended particulate levels and gas-tric cancer that appeared to be independentof economic 'status. It should be noted, how-ever, that this study did not take into ac-count the smoking habits of the deceased.
Among white males and females between50 and 69 years of age, the death rate fromgastric carcinoma was 27 per 100,000 popu-lation for those living in the area with theleast suspended particulates, half again ashigh for those living in the next most pol-luted area, and one and one-half times ashigh for those living in the most pollutedarea. See Table 11-4 and Figure 11-6.
The Nashville Air Pollution Study by Zeid-berg et al.?. 39 used sulfation and dustfalldata from 123 sampling stations, and sulfur
Table 11-2.AVERAGE ANNUAL DEATH RATES PER 1,000 POPULATION FROM ALL CAUSES ACCORD-ING TO ECONOMIC AND PARTICULATE LEVELS, AND AGE: WHITE MALES, 50-69 YEARS OFAGE, BUFFALO AND ENVIRONS, 1959-1961.
EconomicParticulate Level
Level1. (Low) 2 3 .4 (High) Total
1 (low) 36 41- 52 432 24 27 30 36 298 24 26 33, 254 20 22 27 225 (high) 17 21 20 19
Total 20 24 31 40 26
159
dioxide concentrations and soiling indicesfrom 36 stations. All codable deaths regis-tered between 1949 and 1960 (32,067) werethen distributed among census tracts ratedaccording to high, moderate, and low pollu-tion levels, and upper, middle, and lower eco-
ao
-10
01 2 3
PARTICULATE LEVELS(all economic Mveb)
FIGURE 11-4. Averave Annual Death Rate from AllCauses. (The graph shows the daath rate per 1,000population for white males between 60 and 69 yearsof age for four levels of particulate matter, Buffaloand environs, 1959-1961.)
nomic classes, and then further coded by age,sex, race, and underlying cause of death.Standardized mortality ratios (for total res-piratory disease, and for pneumonia, influ-enza, bronchitis, emphysema, tuberculosis,and lung and bronchial cancer) were then
140
20
100
so
60
40
20
02' 3
PARTICULATE LEVELS(all economic levels)
4
FIGURE 11-5. Average Annual Death Rate from Asth-ma, Bronchitis, or Emphysema Indicated on theDeath Certificate. (The graph shows the deathrate per 100,000 population for white males be-tween 60 and 69 years of age for four levels of par-ticulate matter, Buffalo and environs, 1969-1961.)
Table 11-3.AVERAGE ANNUAL DEATH RATES PER 100,000 POPULATION FROM CHRONIC RESPI-RATORY DISEASE ACCORDING TO ECONOMIC AND PARTICULATE LEVELS, AND AGE: WHITEMALES, 50-69 YEARS OF AGE, BUFFALO AND ENVIRONS, 1959-1961.
EconomicParticulate Level
Level1 (Low) 2 3 4 (High) Total
1 (low) Oa 126 188 1332 64 75 96 105 843 66 61 103° 644 36 47 114 625 (high) 42 63 Oa 50
Total 44 62 94 129 72
a Rate based on less than five deaths.
2 3 4(HIGH)
PARTICULATE LEVELS(economic levels 2, 3, and 4)
FIGURE 11-6. Average Annual Death Rate from Gis-tric Cancer. (The graph shows the death rate per100,000 population for white males between 50 and69 years of age for four levels of particulate mat-ter, Buffalo and environs, 1959-1961.)
related to the pollution indices obtained dur-ing 1959. The statistically significant mor-tality increases were those for all' respira-tory diseases related to sulfation and soil-ing; lung and bronchial cancer mortality, andbronchitis and emphysema mortality werenot clearly related. "High" pollution in thesestudies referred to soiling at more than 1.1coh units/1,000 linear feet and SO2 concen-trations of more than about 30 fag/ma (.01ppm). A later paper 40 derived from the samestudy period, analyzed infant and fetal death
rates between 1955 and 1960. For white in-fant mortality, significant regressions wereobtained for sulfation; dustfall (alone, or asan interaction variable) was the most fre-quently related variable. In the study, ac-count was not taken of smoking habits ofthe deceased; also, the "middle class" groupcovered a relatively large segment of thedecedents.
It is intresting to note that the associa-tion between suspended particulate levelsand gastric cancer in the Buffalo study whichappeared to be independent of economic sta-tus was also observed in the Nashvillestudy."
c. Geographic Variations in MorbiditySpecial StudiesIt has been postulated that the study of
records of illness rather than mortality-should be more fruitful in defining subtleeffects, since morbidity is an earlier andmore sensitive index of deviation from nor-mal health. A much larger insult must pre-sumably be given to the body to cause deaththan to cause illnesp. ,Routinely collectedmorbidity data are, however, not generallyavailable. Data may occasionally be obtainedfrom group insurance plans, hospitaladmis-sion records, or existing school records. Sincesuch data are usually not collected in a uni-form, precise manner, most morbidity stud-ies require expensive and time-consumingfield surveys with questionnaires or actualmedical examinations of the subjects.
Morbidity studies of adults involving long-term exposures are frequently not as useful
Table 11-1.AVERAGE ANNUAL DEATH RATES PER 100,000 POPULATION FOR GASTRIC CANCERACCORDING TO ECONOMIC AND PARTICULATE LEVELS: WHITE MALES, 50-69 YEARS OFAGE, BUFFALO AND ENVIRONS, 1959-1961.
EconomicLevel
Particulate Level
1 (Low) 2 3 4 (High) Total
1 .(low) 0(0) 63(10) 136(8) 77(18)2 45(5) 41(12) 48(10) 84 (8) 50(35)8 39(9) 51(6) 51(2) 44(17)4 15(3) 38(9) 63(5) 33(17)5 (high) 26(5) 16(3) 0(0) 20(8)
Total 26(13) 84(33) 53(31) 42(95)
Figures in parentheses indicate numbers of deaths'
?.
161
I
as desired due to the presence of complicat-ing factors such as occupation and smoking.Accordingly, Anderson 3° has recommendedthat children and housewives be used to de-termine the health effects of air pollution.
A study was conducted by Petri lli et a1.41in Genoa, Italy, which followed Anderson'srecommendation. The subjects were womenover 65 years of age, nonsmokers who hadlived for a long period in the same area andwho had no industrial work experience. Eco-nomic and social conditions in the areas ofresidence were thus considered as well asthe levels of pollution in the areas of theirresidence. Pollutant measurements were car-ried out between 1954 and 1964 in 19 differ-ent areas, and morbidity indices. were cal-culated for 1961 and 1962 for this popula-tion, which received free medical care fromthe municipality and therefore was undercontinuous medical observation. There wasa significant correlation between the fre-quency of bronchitis with mean annual sul-fur dioxide levels (r =0.98) and a nonsig-nificant correlation for mean annual sus-pended matter (r -0.82) and mean annualdustfall (r =0.66).
Toyama," in a comprehensive study of airpollution and its health effects in Japan,charts the age-standardized morbidity rates(per thousand) secured by interview surveyin 1961, and describes a gradient of respira-
-I
-I
0
tory disease morbidity from the highly in-dustrialized (and presumably polluted) areasto .the rural areas of Japan. Further, thepulmonary disease morbidity ratio washigher in the industrialized, polluted areasthan were the ratios for other disease group-...m,g& The gradient was not noted for cardio-vascular diseases nor for gastrointestinaldiseases. Unfortunately, specific pollutantconcentrations are not clearly indicated toaccompany these data on morbidity. Theage-standardized morbidity rates per thou-sand for several cities in Japau are shownin Figure'11 -7.
Holland et W." studied the prevalence ofchronic respiratory disease symptoms andperformance of pulmonary function tests ina comparative study of outdoor telephoneworkmen in London, in rural England, andon the east and west coasts of the UnitedStates. Types of occupational exposure, useof cigarettes, and socioeconomic matchingwere considered. The annual mean concen-tration of suspended particulate matter inthe British exposures was approximately 200Fg/m3, and approximately 120 µg /m3 in theAmerican case. For sulfur dioxide, the meanconcentrations were: in London 300 110113(-10.1 ppm), in rural areas of England 60µg /m8 (-0.02 ppm), and in the UnitedStates between 30 µg /m' and 120 µg /m'(-0.01 ppm and 0.04 ppm). Persistent
RESPIRATORY CARDIOVASCULAR GASTROINTESTINAL
I 1
10 20 30 o 10 0
RATE PER THOUSAND
KAWASAKI
YOKOHAMA
FUJINO
KAINAN
DAITO
10 20 30
FIORE 11-7. Age-Standardized Morbidity Rate per 1,000 for Three Types of Diseases in Japan." (Themortality rate for respiratory diseases shows a clear correlation with pollution levels. There is no such clearcorrelation for cardiovascular or gastrointestinal disorders.)
162 kv..A70
cough, phlegm, and chest_ illness' episodes andincreased sputum volume were all signifi-cantly more frequent in men (between theages of 50 and 59) in the London area thanin rural England; and pulmonary functionwas poorer in relation to the levels of smokeand sulfur dioxide. It is possible, therefore,that an increase in smoke concentration from120 pg/m8 to 200 pg/m3 (with an equivalentincrease in sulfur dioxide level) increasesthe risk to older workers of deteriorated pul-monary function and increased symptomatol-ogy of chronic respiratory disease. Table11-5 summarizes some of the results ob-tained.
Holland and Reid " reviewed respiratorysymptoms, sputum production, and lungfunction levels in post office employees bothin central London and in peripheral towns.Over the age of 50, the London men had morefrequent and more severe respiratory symp-toms, produced more sputum, and had sig-nificantly lower lung function tests. Socioeco-
nomic factors were presumed the same, theoccupational exposures were homogenous,and corrections were applied for smoking.There were some physique differences in therural areas and allowances were made forthese in the statistical evaluation. Unfortu-nately, no quantitative air quality determina-tions accompanied these results. The authorsnevertheless concluded that the most likelycause of the difference in respiratory mor-bidity between the men working in CentralLondon and those in the three rural areaswas related to the differences in the local airpollution.
In a group of Canadian veterans studiedby Bates et a relationship between airpollution and both bronchitis and pulmonaryfunction measurements has been reported.There are, unfortunately, inadequate dataon the levels of smoke, sulfur dioxide, andother pollutants, in the four Canadian citiescompared, to derive specific relationships be-tween the levels of these pollutants and the
Table 11-5.-RESPONSE OF TELEPHONE WORKERS IN THE U.K. AND U.S.A. TO AIR '?OLLUTION."
United KingdOm United States
London Ruralareas
Baltimore.WashingtonWestchester
County
San FranciscoLos Angeles
Age Age Age Age Age Age Age Age40-49 60-69 40-49 60-69 40-49 60-69 40-49 60-69
Number of men examined 118 187 267 159 896 229 861 119Persistent cough and phlegm
(percent) 25.7 88.7 24.0 18.9 22.2 25.8 21.6 24.4Persistent cough and phlegm and
chest illness episode (percent)___ 10.6 10.9 7.5 5.0 6.8 7.0 4.0 7.6FEV1.0 (liters) mean values:
Non smokers 2.8 2.6 8.0 2.8 8.6 8.1 3.7 8.8Cigarette smokers:
1-14 per day 2.6 2.8 2.8 2.6 8.4 8.015-24 per day 2.6 2.2 2.8 2.5 8.2 2.8 8.4 2.826 or more per day 2.5 2.1 2.7 2.5 8.2 2.9
Sputum volume 2 cc. or more(percent) 28.9 42.9 22.1 28.5 7.1 10.0 8.6 14.8
Suspended particulate matter,24 hr (pg/m):
Mean 220 200 120. 120Maximum 4000 8000 500 840
Sulfur dioxide, 24 hr. (pg/In),ppm in parentheses:
Mean 290 (0.1) 60 (0.02) 110 (0.04) 80 (0.01)Maximum 8700 (1.8) 740 (0.26) 716 (0.26) 170 (0.06)
Vy Y 471 168
prevalence or exacerbation of disease or thedeterioration of pulmonary function. How-ever, there is an association in the "dirty"cities (Montreal and Toronto) versus the"clean" cities (Halifax and Winnipeg) ofincreased prevalence and severity a bron-chitis, and poorer pulmonary function per-formance.
Anderson and Ferris 46.47 completed a com-parison of respiratory disease incidence andair pollution in three residential areas ofBerlin, New Hampshire, by prevalence sur-vey. Subjects who were nonsmokers andthose who were moderate smokers were spe-cifically evaluated. The different levels ofair pollution at one or more stations in eacharea were recorded in relation to monthlydustfall and to sulfur dioxide concentration.Prevalence of respiratory disease and pul-monary function determinations (FEVI.Gand peak expiratory flow rate) were made.The mobility of the population, variationsof concentrations of pollutants within a givenarea, possible effects from the area of occu-pation, and differences in the in-home en-vironment, were considered as contributorsto the lack of consistent effect on the studiedparameters of air pollution. In a laterstudy'" these authors compared this "pol-luted" town in New Hampshire with a con-trol community in British Columbia andagain found an obscuring of the effects of airpollution on respiratory symptoms and pul-monary function performance, suggestingperhaps the overwhelming effect of cigarettesmoking in symptom 'production. It shouldbe noted, however, that the pollution levelsand the ranges were possibly too low or toosmall to show a relationship.
The Nashville air pollution study'-. re-viewed total morbidity in relation to air pol-lution. A wide matrix of sampling stationswas used to group the residence of individ-uals into areas of high, moderate, and lowpollution according to geometric mean an-nual measurements, and the morbidity datawere secured by home interview. Significant"direct correlations" of total morbidity withlevels of pollution (measured by soiling in-dex and 24-hour sulfur dioxide levels) wereobserved for individuals over 55 in the mid-dle socioeconomic class. Cardiovascular dis-
164
eases were directly correlated with the aero-metric parameters. There was no statisticalevidence of increased respiratory diseasemorbidity or morbidity of other organs andsystems. The same qualifications noted forthe mortality data in this study apply tothese data on morbidity.
d. MorbidityIncapacity for WorkDohan " reviewed the incidence of res-
priatory disease producing absence fromwork in a population of women employedin several branches of an electronics com-pany in the eastern part of the UnitedStates. Pay scales were roughly equivalentand presumptions were made, therefore, thatthe socioeconomic status and smoking pat-terns were uniform. Air measurements weremade from areas near the town of employ-ment (for suspended particulate sulfates, ni-trates, copper, zinc, vanadium, nickel, andacetone-soluble organic matter, as well astotal suspended particulate matter). Ab-sences for a respiratory illness in excess of 7days were calculable from company-employ-ment and health-insurance records. Therewas a significant correlation of respiratorydisease absence frequency with the concen-tration of suspended particulate sulfates,with 24-hour values measured biweekly; al-though the level of total suspended particu-late matter ranged from 100 µg /m3 to 190µg /m3 in the various cities, a correlation wasnot demonstrated. The implication of thesignificantly correlated datum "suspendedparticulate sulfate" is not clear, as it might,for example, be an index of the communityfuel consumption or an index of sulfur di-oxide irritation.
Burn and Pemberton 34 reviewed the in-creased number of certificates of incapacityissued to workers in Salford in relation tosmog episodes. When mean daily smoke pol-lution, based on data from five samplingstations, exceeded 1,000 µg /ms for 2 consecu-tive days, the number of "bronchitis cer-tificates". issued exceeded the expected num-ber by a factor of two, on four or five oc-casions in 1958.
During 1961-1962 a study of the inci-dence of incapacity for work was conductedby the British Ministry of Pensions and Na-
tional Insurance." The population coveredwas representative of the working popula-tion of England and Wales. Rates of sick-ness absence for bronchitis, influenza, arth-ritis and rheumatism were related to in-dices of pollution. There was a significantcorrelation between bronchitis incapacity inmiddle-aged men (35-54) and the averageseasonal (October through March) levels ofsmoke and sulfur dioxide in high-densityresidential districts; based on 24-hour meas-urements. For Greater London, there was asignificant correlation between bronchitisincapacity and both smoke and sulfur di-oxide for all age groups taken together, andfor men aged 35 to 54 and 55 to 59. It isinteresting that there was also more incapac-ity from arthritis and rheumatism in areas'having heavy smoke pollution. Influenza in-capacity was greater in those areas withhigher pollution levels over Great Britainas a whole but not within the Greater Lon-don conurbation, nor was there in this lat-ter area' any association between pollutionand psychosis or psychoneurosis. The low-est bronchitis inception rates related tosmoke levels between 100 ter/m3 and 200µg /m3 and to sulfur dioxide concentrationsbetween 150 µg /m3 and 250 µg /m3 (0.053ppm and 0.081 ppm). The highest valuesrelated to particulate concentrations of 400µg /m3 and 400 aims (0.14 ppm) sulfur di-oxide.
Verma et al.,52 presented information onillness absences in relation to air pollution.Illness data for the employees (males andfemales, ages 16 through 64) of a metro-politan New York insurance company wereobtained through the records of the person-nel department. They included medical his-:tory, X-ray information, and laboratory re-sults obtained by the medical department ofthe company, and were classified by absencesdue to respiratory illness and to nonrespira-tory illness. Mean daily concentrations ofair pollution and meteorologic data were se-cured from the monitoring system of metro-politan New York: smoke shade, sulfur di-oxide, and carbon monoxide content were re-ported. The data for the 2 years 1965 and1966 were examined statistically and severalconclusions were reached. There was a
strong time dependence,. and .yearly cyclicalbehavior; when this factor was removedthere remahled no strong positive relation-ship between respiratory absence and thepollution variables studied. Respiratory ill-ness absence rates were at their highestlevel when sulfur dioxide and smoke shadelevels were both high on cool days; and alag effect for respiratory absences was notnoted.
3. Studies of ChildrenComparisons of the prevalence of respira-
tory disease in areas of varying pollutionlevels have been made to delineate the roleof air pollution and specific pollutants. Aproblem common to all the studies is thedifficulty in guaranteeing that the areas aresimilar (except for air pollution) in all fac-tors that might affect the prevalence ofdisease.
Because studies on adults tend to be com-plicated by smoking habits, changes of oc-cupations, and changes in address over aperiod of years, several studies have been.directed at effects of air pollution on schoolchildren. The advantages of utilizing chil-dren for research on the primary etiologiceffects of air pollution were first noted byReid 53 several years ago; Anderson 32 hasmost recently reaffirmed this view. A majorelement of concern is that deleterious effectson the respiratory system of very youngchildren may have an effect on the subse-quent evolution of the chronic bronchitis syn-drome in the adult population.
The relationships of respiratory infectionsto long-term residence in specific localitieshave been studied in England by Douglasand Waller." Levels of air pollution, interms of domestic coal consumption records,were used to classify four groups; the auth-ors include an evaluation of the validity ofthis method at the end of their report. Thehistories of 3,866 children born during thefirst week of March 1946 were followed until1961, when the children were 15 years ofage. Social class composition of these chil-dren did not differ significantly from areato area. Measured concentrations for smokeand for SO2 in 1962 and 1963 were coin!.pared with the earlier prediction of pollu-tion intensity based on the coal consumption
165
data, and indicated an overlap for the greaterLondon area of low and moderate groupings;for other areas, the predicted gradient ofconcentrations was affirmed. Because of theage of the subjects, smoking was apparentlynot considered in this evaluation. In 1965,19 percent of the boys and 5 percent of thegirls, aged 11 to 13, smoked at least onecigarette a week regularly."
In the Douglas and Waller study, the gen-eration of pollutants in the indoor home en-vironment (e.g., by heating and cooking)was not considered. Interviews were con-ducted with the mothers when the childrenwere 2 and 4 years of age; information wasobtained about upper and lower respiratoryillness and recorded hospital admissions forthese and other causes. Data about colds,coughs, and hospital admissions were alsogathered by school doctors at medical ex-aminations when the children were 6, 7, 11and 15 years of age. Between the ages of61/2 and 101/2, special records for causes ofschool absence exceeding one week were re-viewed with the mothers. A total of 3,131families remained in the same pollution areathroughout the first 11 years of this study.The conclusions of the study were that upperrespiratory tract infections were not relatedto the amount of air pollution, but that lowerrespiratory tract infections were. Frequencyand severity of lower respiratory tract in-fections increased with the amount of airpollution exposure, affecting both boys andgirls, and with no differences detectable be-tween children of middle class and workingclass families. This association was foundat each of the examination ages, includingage 15. At age 15, persistence of rales andrhonchi (chest noise), possibly the prodromeof adult chronic respiratory disease, wassome tenfold less in the very low pollutionarea, and a factor of two less in the low pol-lution area than that in the high pollutionarea. If the 1962-1963 measured concentra-tions for smoke and SO can truly be extrap-olated to the 15-year respiratory illness sur-vey, then these British school children ex-perienced increased frequency and severityof lower respiratory diseases in associationwith annual mean smoke concentrations
ranging above 130 µg /m' and SO2 above 130aims (0.046 ppm).
The lower respiratory tract findings ofDouglas and Waller were confirmed in astudy by Lunn et al." The patterns of res-piratory illness in school children of the agegroup 5 to 6 have been studied with ref-erence to residence in four areas of Sheffield.Mean daily smoke levels measured in eachof four areas ranged from 97 µg /m' in theVow" area to 301 µg /m' in the "high" area;SO, concentrations were respectively 123µg /m' (0.043 ppm) and 275 µg /m' (0.096ppm) in the two areas, during 1963-1964.Somewhat lower pollution levels were notedthe following year, although the gradient be-tween the districts was preserved. Ques-tionnaire to the parents, physical examina-tion, observation for the presence of nasaldischarge, examination of the eardrums, andrecording of both the forced expiratory vol-ume of 0.75 seconds (FEVo.n) and theforced vital capacity (FVC) , were completedduring each of the summer terms of 1963,1964, and 1965. Several socioeconomic fac-tors were compared for the various districts;smoking was appropriately disregarded forthis age group; internal home environments,or differences in home heating systems, werenot reported. The authors conclude thatthere is an association with the levels of at-mospheric pollution and chronic upper res-piratory infections (as indicated by muco-purulent nasal discharge, history of threeor more colds yearly, or scarred or perfo-rated eardrum). Further, lower respiratorytract illness (measured by history of fre-quent chest colds or episodes of bronchitisor pneumonia) was similarly associated.Functional changes, in the form of reducedFEV0.75 ratios emerged where there was apast history of pneumonia or bronchitis, ofpersistent or frequent cough, or of coldsgoing to the chest. There appears, there-fore, to be a persistence of respiratory dys-function, even in the absence of high-pollu-tion extant at the time of the functiontesting. The lowest "effect" level for smokeand SO: is not clearly indicated by thisstudy, but the increased association of "res-piratory infections" in school children canbe detected for areas whose mean daily fig-
ures exceed about 100 ag/m3 for smoke and120 µg /ma (0.042 ppm ) for SO:.
The exacerbation of acute respiratory ill-ness of school children in Ferrara, Italy, hasbeen studied by Paccagnella et al." Air pol-lution measurements from 1959 through1964 permitted definition of high, medium,and low zones of pollution. School childrenin the age range 7 to 12 had daily examina-tions, and the date of onset of acute respira-tory disease was recorded. Although climaticconditions were related to changes in pollut-ant levels, the onset of acute respiratory dis-ease in the children was not correlated sig-nificantly with changing air pollution values,except in the poorest socioeconomic area.The pollutant values for this community are,however, lower than those encountered inthe British studies previously discussed (20µg /m, to 45 µg /m3 annual mean). In fact,these are levels which are lower than manyrural values in the United States.
Toyama 42 studied two groups of schoolchildren, 10 to 11 years old, in Kawasaki,Japan. Sulfation rates at the school in themore polluted area varied from 0.5 to 1.9and averaged 0.9 mg/100cm2-day Pb02; nosulfation rates were given for the school inthe area of lower pollution. Dustfall wasconsiderably less in the area of lower pol-lution (ranging from about 5 tons/km=-mo. to 15 tons/km2 -mo.) * than in the morepolluted area (ranging from about 15 tons/km2-mo. to 70 tons/1=2-mo.). The childrenfrom the more polluted area had a higherfrequency of nonproductive cough, irritationof the upper respiratory tract, and increasedmucus secretion. Whether the effect was dueto oxides of sulfur or particulate matter can-not be determined from this study.
A study by Manzhenko 58 of upper respira-tory tract conditions in school children inIrkutsk is difficult to relate to the Sheffieldstudy. However, the higher incidence of res-piratory tract conditions and the undefinedabnormal X-ray findings in these children'rlungs are disturbing evidence of the poss.bility of an association between serious res-
*Ia the United States, dustfall is measured in
piratory disease and residence in a pc flutedcommunity.
4. Studies of Pulmonary FunctionHolland et al." report decreased perform-
ance of the FEV1.0 test in London and Brit.ish rural outside telephone workers com-pared with their American counterparts.For both groups the FEV was further de-creased in relation to smoking intensity.FEV differences within the United Kingdomworkers (i.e., London versus rural) couldalso be related to the sulfur dioxide concen-trations accompanying the particulate lev-els. A more detailed discussion of the studyappears in Section C-4.
Toyama 42 reported measurements of peakflow rate and total vital capacity perform-ance in Japanese school children in areas ofdiffering air pollution, measured monthly;fluctuations were observed in the mean peakflow rates of children attending schools andliving in 'polluted industrial areas; and thevariations were smaller for children inclearer areas. Total vital capacity was notsignificantly differentbetween pupils of thevarious schools. There was a substantialdifference in peak flow rates between thetwo school districts at times of highest pol-lution. When pollution "values were lowest,the differences were less. The lowest valuesrelated to dustfall measurements of .60tons/km2-mo.* and daily sulfur dioxide levelsequivalent to 20 4/cm2 (lead candle meas-urement).
In Osaka, Watanabe 20 studied the peakflow rate and vital capacity performances bythe children of schools enduring differing airpollutant concentrations. It was noted thatindividual peak flow rates were more mark-edly decreased in the winter months (Sep-.tember to December, 1963) for the schoolin the highly polluted area than for theschool in the low pollution area. Daily meanconcentrations of both dustfall and sulfurdioxide concentrations were twice as greatin the polluted area as in the unpolluted area.
In a comparison by Prindle et a" of pul-
*In the United States, dustfall is measured intons/mi'-mo. tons/mikmo.
4 }
175 167
r
monary function and other parameters intwo Pennsylvania communities with widelydifferent air pollution levels, average airwayresistance and specific airway resistancewere measured in persons 30 years of ageand older. These measurements were per-formed at several stations in each of the com-munities and indicated differences betweenthe high-pollution and low-pollution commu-nities which were probably related to thesixfold greater dustfall. However, smokingand occupation were not accounted for.
In the paper by Lunn et al.," Sheffieldschool children were shown to have reducedFEV0.75 and FVC ratios in the area of high-est pollution. The measurements were madeduring the summer, when pollution levelswere low and apparent incidence of acuterespiratory infection was diminished, sug-gesting, in contrast to the Japanese studiesreferred to above, that there may - be per-sistence of the respiratory function deterio-ration in relation to residence in the area ofhigh pollution; mean daily averages meas-ured at a single station were: smoke, 300µg /m'; SO2, 275 µg /m' (0.096 ppm).
The studies relating morbidity and deteri-oration in pulmonary function to particulatelevels cover effects which are also included
Level III of the World Health Organization's "guides to air quality."235, Studies of Panels of Bronchitis Patients
Lowther e° related several episodes ofacute urban pollution to worsening of con-dition in a group of bronchitic patients, wellstudied in a registry at St. Bartholomew'shospital. Changes in their symptomatolagywere recorded in a daily diary and acuteworsening in significant numbers of thegroup was associated with daily rises in airpollution above 300 µg /m' of smoke and 600pg/m3 (021 ppm) of sulfur dioxide: Figure11-8 shows graphically the effects observedon 29 bronchitic patients of high pollutionlevels in January 1954
Angel et at." reviewed the occurrence ofnew reepiratory symptoms in; men, Workingin factories and in offices, most of Whomhad prior evidence of chronic bronchitis.The study, group of 85 men obserYed through+ha + L W ttf aao_i no .1 -
out apparent classification of either smokingpatterns or possible occupational or residen-tial exposure differences. Increased sputumproduction, deterioration of pulmonary func-tion performance (FEV1.0), and the morefrequent occurrence of respiratory symp-toms classified as "upper" (coryza, influenza,and acute respiratory disease), and "lower"(chest colds, bronchitis, wheezy attacks,,pneumonia) were all associated with increases in both smoke and sulfur dioxideconcentrations. There was frequently diffi-culty in defining an exacerbation of diseasein those individuals already experiencingchronic bronchitis. During this period, ill-ness peaks (attack rate) may have occurred:
with weekly mean concentrations of smokeexceeding 400 µg /m' and of sulfur dioxideexceeding 460 µg /m' (0.16 ppm) ; weeklymean concentrations were calculated usingthe highest daily mean occurring each weekat each of 13 locations in the area:
Bierstecker e3 surveyed male municipalemployees in Rotterdam for symptoms ofbronchitis and for peak flow meter perform-ance, and reviewed years of residence inRotterdam versus years of residence in anonurban environment as well as smokinghabits. The individuals with bronchitissymptoms were matched with individualswithout such symptoms but with similar ageand background. Sigiificant differences re-lated to heavy cigarette smoking, but noreliable statistical indication of an effect ofurban or nonurban residence in the produc-tion of symptoths was detectable. Since par-ticulate levels in Rotterdam are very low, therange of difference between particulate levelsin Rotterdam' aifd the nonurban environmentmay have been close to minimal.
Fletcher et al." followed 1,136 workingmen aged 30 to 59. in West London' by sur-veys at 6-month interval& The surveys in-cluded collection and measurement of morn-ing sputum volume, FEV, and respiratorysymptom j questionnaires. While expectedpatterns of decline in lung function with ageoccurred and this was the most rapid incigarette smokers with low lung fuction tostart with, an unexpected finding was a de- .
MEANTEMP oF
SMOKEmg / m3
NUMBEROF
PATIENTSWORSE
BETTER
50
45
40
35
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
4
0
4
8
18 17 18 19 20 21 22
JANUARY 1954
100
90RH
60 PERCENT80
70
0.6
0.5
0.4
0.3
0.2
0.1
SO2PPm
FIGURE 11-8. Effect on Bronchitic Patients of High Pollution Levels (January 1954)." (The figure repre-sents the effect on bronchitic patients of increased pollution levels; patients stated whether they regardedtheir condition as "worse" or better".)
sistent in the winter samples, but shOwed asignificant trend in samples taken togetheras well as in the winter samples. (Trenddata are based on 825 men whO attendedat least nine periodic examinations.) Theauthors felt this was possibly due to a de-cline in air pollution in London. They pre-sented data on trends in SO, and black sus-pended matter which indicated that there isa consistent downward trend in particulatepollution (highly significant) but a lesssteady decline in 502. ' .
This unique set of data could mean thatwith a decrease of smoke 'pollution (yearlymean) from 140 pgim3 to 60 isg/ins, there is
that of the decrease in smoke. Possiblechanges in cigarette tars, in methods . ofsmoking and in techniques for collecting asample, or other factors, could have influ-enced this result.
1st hour sputum volumeIn men ofconstant smoking habits
1961.
Summer 1.65Winter 1.38
D. SUMMARYThis chapter reviews epidemiologic studies
1965 1968 1964 1965 1966
0.83 0.93:0.93 0.83 0.721.27 1.20 1.18 0.70
of the relationship between pollutant con-centrations and their effects on health. In-
indicators were under review, and in thesecases it is possible to state pollutant levelsat which an effect is noted. However, suchvalues cannot be taken to mean that effectswill not be noted at lower concentrations.Most studies involving long-term effectsusing a geographic area comparison will usethe cleanest area as the "control" areaagainst which mortality and morbidity dif-'ferentials are to be found. This necessarilyassumes that this "cleanest" area itself doesnot have any effects from its level of pollu-tion. Conversely, some studies have com-pared areas with very low particulate load-ing or with very limited ranges of differ-ences. It is not possible to dethonstrate anyrelationship under conditions of minimumvalues, or minimal differences.. Table 11-6summarizes the epidemiologic studies re-viewed according to the several indices.
From the material reviewed in this chap-ter, a selection has been made of data fromthose studies which furnish the best quan-titative information that we have availableat the present time. Levels are given in themeasurement system used in the originalobservations, since conversion from onemethod to 'another is not recommended. At-tention should be given to the difference be-tween British "smoke" and American "sus-pended particulate" measurements. Both aregiven in micrograms per cubic meter of air,but they are not identical. Limited data in-dicate that the American values may behigher in the same situation. In makinguse of these data,- attention must also begiven to the averaging' time which was em-ployed 'in the original observation. Long-term averages are, of necessity, considekablylower than selected high daily means in thesame locations.
British studies of acute episodes of in-creased pollution show excess deaths occur-ring at smoke levels from 750 1.4g/m3 to 2,000pg/ms. High 802 levels are, of course, con-currently present :The excesses of mortal-ity are. always accompanied by a very largeincrease in Illness, -2nninly exacerbations ofchrOnic eonditions; Similar:: but less spec-tacular ATIktlILISt in' Mgtv vnni,
Lawther, in reviewing a long series of ob-servations on the condition of bronchiticpatients, estimated that they tended to be-come worse when daily levels of smoke ex-ceeded 300 µg /m' with SO2 over 600 pg/ms.Angel et al. made somewhat similar obser-vations with smoke above 400 µg /m' andSO: over 460 µg /m'.
Winkelstein found in Buffalo that in-creases in the mortality rate were signifi-cantly linked to higher levels of suspendedparticulate pollution. His studies showedthat mortality from all causes, from chronicrespiratory diseases, and from gastric car-cinoma increased from the lowest of hisfive levels of pollution (less than 80 µg /m')through the three higher ranges, after theeffects of socioeconomic status had been con-sidered. Zeidberg found in Nashville sig-nificant increases in all respiratory deathsat soiling levels over 1.1 cohs annual aver-age. Neither of these studies took smokinghabits into account, and the Nashville studyonly . partially allowed for socioeconomicfactors.
. Studies of illness in relation to residencein more- and less-polluted areas contributeadditional information. Fletcher et al. noteda proportional decline in the production ofmorning sputum in chronic bronchitics inWest London from 1961 to 1966 as smokepollution in their residence areas declinedfrom 140 µg /m' annual mean. Douglas andWaller found an increase in frequency andseverity of lower respiratory illness at smoke
;and SO: levels over 130 µg /m® annual aver-age. The Sheffield study by Lunn et al.'shows similar differences occurring. withsome morbidity measures between about100 pg/ins and 200 pg/ms of smoke, and forothers between 200 µg /m' and 300 µg /m'annual average.
A study of British workmen found in-creased respiratory illness absence in areasw_ ith smoke levels in excess of 200 lg. g/m3..
Physiologic studies of lung function havealso been made in- both adults and children.On the basis of present limited knowledgeit appears that the alterations found may be
rs'
Table 11-6 (continued).SUMMARY TABLE OF EPIDEMIOLOGICAL STUDIES
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8
8. Japan
4. Pennsylvania,2 com-munities.
6. Sheffield, U.K. 100
I. Studies of panels of bronchitic patients:1. London, 300
November,1965-May,1966.1
2. U.K., October, 4001962-April,1963.
3. Rotterdam, n.a.'Netherlands.
4. London 140 pg/m3decliningto60 penis.
Peak flow rates decreased more in 20winter for children in pollutedareas than in less polluted areas.
Possible relation of dustfall and 69SO: differences in average andspecific airway resistance ofsubjects in the two com-munities.
275 Reduced FEVom and FVC in 66areas of highest pollution.Possible persistence of respira-tory function deteriorationrelated to residence in area ofhigh pollution.
>600 Acute worsening of symptoms in 60bronchitis patients.
460 : Possible increase in respiratory 62disease attack rates.
n.a. No indication of residence effect 68on bronchitis symptoms.
200 pg/m3 Decrease in morning sputum 64declining volume with decreasing airto pollution levels in bronchitis160 pgim3. patients under observation dur-
ing 6 years.
study shows reduced pulmonary function inthe children in the most polluted area, i.e.,where smoke concentration is above 300.pg/m2. Studies in Japan show a decreasein pulmonary function in school children liv-ing in areas of high dustfall as comparedwith those living in low duatfall areas.. InOsaka the dustfall levels were 6.5 gm/m2-month and 13.3 gm/m2-month.
The analyses of the numerous epidemio-logical studies discussed clearly indicate anassociation between air tiollution.1, as aim-
severity. This association is most firm forthe short-term air pollution episodes.
There are probably no communities whichdo not contain a reservoir of individuals withimpaired health who are prime targets forthe effects of elevated levels of particulatematter and sulfur oxides. However, to showsmall changes in deaths associated with co-incident higher levels of air pollutants re-quires extremely large populations. In smallcities, these small changes cannot be de-tected
in Relation to Air Pollution." Arch. Environ.Health. 18:636-643, 1969.
53. Reid, D. D. "Air Pollution and Respiratory Dis-ease in Children." In: Bronchitis, Second In-ternational symposium, Groningen, The Nether-lands, April 22-24, 1964.
54. Douglas, J. W. B. and Waller, R. E. "Air Pol-lution and Respiratory Infection in Children."Brit. J. Prevent. Soc. Med. 20:1-8, 1966.
55. Holland, W. W. and Elliott, A. "Cigarette Smok-ing, Respiratory Symptoms, and AntismokingPropaganda : an Experiment." Lancet 1:41-43,1968.
56. Lunn, J. E., Knowelden, J., and Handyside,A. J. "Patterns of Respiratory Illness in Shef-field Infant School Children." Brit.- J. Prevent.Soc. Med. 21:7-16, 1967.
57. Paccagnella, B., Paranello, R., and Pesarin, F."The Immediate Effects of Air Pollution on theHealth of School Children in Some Districts ofFerara." Arch. Environ. Health. 18:495, 502,1969.
58. Manzhenko, E. G. "The Effect of AtmosphericPollution on the Health of Children." Hyg. Sara.31:126-128, 1966.
59. Prindle, R. A., 'Wright, G. W., McCaldin, R. 0.,Marcus, S. C., Lloyd, T. C., and Bye, W. E."Comparison of Pulmonary Function and OtherParameters in Two Communities with WidelyDifferent Air Pollution Levels." Am. J. PublicHealth 53:200-218, 1963.
60. Lawther, P. J. "Climate, Air Pollution, andChronic Bronchitis." Proc. Roy. Soc. Med. 51:262-264, 1958.
61. Waller, R. E. and Lawther, P. J. "Some Obser-vations on London Fog." Brit. Med..). 4952:1356-1358, Dec. 3, 1955.
62. Angel, J. H.Fletcher, C. M., Hill, I. D., andTinker, C. M. "Respiratory Illness in Factoryand Office Workers." Brit. J. Diseases Chest59:66-79, 1965.
63. Biersteker, K. "Air Pollution and Smoking asCause of Bronchitis among 1,000 Male Munici-pal Employees in Rotterdam (The Netherlands).Arch. Environ. Health.'18:531-536, 1969.
64. Fletcher, C. M., Tinker, B. M., Hill, I. D., andSpeizer, F. E. "A Five-Year Prospective FieldStudy of Chronic Bronchitis." Preprint (Pre-sented at the 11th Aspen Conference on Re-search in Emphysema June 1968.)
ti
the settleable portion of particulate air pollu-tion. Typical values for cities are 10 to 100tons/mile2-month; as high as 2,000 tons/mile2-month have been measured in the vicin-ity of especially offensive sources. Levels ofdustfall have apparently declined in someAmerican cities, and dustfall measurementsare probably not useful as an index of over-all particulate air pollution. However, dust-fall itself constitutes a nuisance, and itsmeasurement can be used as an index of thedirtiness of air pollution.
Several methods are available for measur-ing suspended particulate concentrations.The most commonly used device is the high-volume sampler, which consists essentiallyof a blower and a filter, and which is usuallyoperated in a standard shelter to collect a24-hour sample. The sample is weighed todetermine concentration, and is usually ana-lyzed chemically. The hi-vol is considered areliable instrument for measuring the weightof total particulate matter. Chemicel analysisof the hi-vol sample, however, may be limit-ed: the filter material may contaminate thesample; different substances in the samplemay react with each other; and losses mayoccur through volatilization of material.Tape *mplers, which collect suspended par-ticulate matter on filters and analyze thesample optically, are also in common use.While these samplers are inexpensive andrugged, they yield data which cannot alwaysbe easily interpreted in terms of particulatemass concentration. Other techniques avail,able for measuring particulate pollution in-clude optical systems, which provide an indi-cation of concentration without requiringthat a sample be taken.
The averaging time used for measuringsuspended particulates is not as significant afactor as it is for gaseous pollutants. Thebasic unit of time is 24 hours.' Values takenover this period may be combined into week-ly, monthly, seasonal, and annual means asrequired. The relationships between dailyand other longer time periods in the UnitedStates is known with some degree of precis-ion, as data exist for a 10-year period.
Most of the data on mass concentrationsof suspended particulates come from theNational Air Surveillance Networks,
182
(NASN), which uses the high-volume samp-ler. NASN currently operates some 200urban and 300 non urban stations, and issupplemented by State and local networks.From the NASN data, the annual geometricmean concentrations of suspended particu-late matter in urban areas range from 60Ag/m3 to about 200 Ag/m3. The maximum 24-hour average concentration is about threetimes the annual mean, but values of seventimes the annual mean do occur. Mean par-ticulate concentrations correlate, in general,with urban population class, but the rangeof concentrations for any class is broad, andmany smaller communities have higher con-centrations than larger ones. For nonurbanareas the annual geometric mean is typicallybetween 10 µg /m3 and 60 µg /me.
...A. Effects on HealthFort ft most part, the effects of particu-
late air pollution on health are related toinjury to the surfaces of the respiratory sys-tem. Such injury may be permanent or tem-porary. It may be confined to the surface, orit may extend beyond, sometimes producingfunctional or other alterations. Particulatematerial in the respiratory tract may pro-duce injury itself, or it may act in conjunc-tion with gases, altering their sites or theirmodes of action.
Laboratory studies of man and other ani-mals show clearly that the deposition, clear-ance, and retention of inhaled particles is avery complex process, which is only begin-ning to be understood. Particles cleared fromthe respiratory tract by transfer to thelymph, blood, or gastrointestinal tract mayexert effects elsewhere. Few studies have in-vestigated the possibility of eye injury byparticles in the air; only transient eye irrita-tion from large dust particles presently isknown to be a problem.
The available data from laboratoryexperiments do not provide suitable quantita-tive relationships for establishing air qualitycriteria for particulates. The constancy ofpopulation exposure, the constancy of tem-perature and humidity, the use of young,normal, healthy animals, and the primaryfocus on short-term exposures in many lab-oratory studies make extrapolation from
190; .
these studies of limited value for the generalpopulation, and singularly risky for specialrisk groups within the population. Thesestudies do, however, provide valuable inform-ation on some of the bioenvironmental rela-tionships that may be involved in the effectsof particulate air pollution on health. Thedata they provide on synergistic effects 'showvery clearly that information derived fromsingle-substance exposures should be appliedto ambient air situations only with greatcaution.
Epidemiological studies do not have theprecision of laboratory studies, but they havethe advantage of being carried out underambient air conditions. In most epidemiologi-cal studies, indices of air pollution level areobtained by measuring selected pollutants,most commonly particulates and sulfur com-pounds. To use these same studies to estab-lish criteria for individual pollutants is justi-fied by the experimental data on interactionof pollutants. However, in reviewing the re-sults of epidemiological investigations itshould always be remembered that the speci-fic pollutant under discussion is being usedas an index of pollution, not as a physico-chemical entity.
In epidemiologcial studies consistency ofresults at different times and places is im-portant in determining the significance ofobservations. However, while polluted air hasmany similarities from place to place andfrom time to time, it is not identical in allcommunities or at all times, and completeconsistency between epidemiological studiesshould not be expected. There are not a largenumber of suitable epidemiological studiesavailable at present, but those that are avail-able show some consistency in the levels atwhich effects were observed to occur.
Considerable data have been presented ona number of air pollution episodes in Londonand in New York City. In reviewing thesedata it should, be remembered that Britishair pollution measurements are not entirelycomparable with American measurements.The only published comparison indicates thatthe British method of measuring particulatestends to give somewhat lower readings thanAmerican methods.
Excess deaths and a considerable increase
in illness have been observed in London atsmoke levels above 750 pg/ms and in NewYork at a smokeshade index of 5-6 cohs. Sul-fur oxides pollution levels were also high inboth cases. These unusual short-term, mas-sive exposures result in immediately appar-ent pathologic effects, and they represent theupper limits of the observed dose-responserelationship between particulates and ad-verse effects on health. -
Daily averages of smoke above 300 pg /mato 400 pg/m3 have been associated with acuteworsening of chronic bronchitis patients inEngland. No comparable data are availablein this country. Studies of British workmenfound that increased absences due to illnessoccurred when smoke levels exceeded 200.µg/ms
Two recent British studies showed in-creases in selected respiratory illness inchildren to be associated with annual meansmoke levels above 120 pg/ms. Additionalhealth changes were associated with higherlevels. These effects may be of substantialsignificance in the natural history of chronicbronchitis. Changes beginning in youngchildren may culminate in bronchitis severaldecades later.
The lowest particulate levels at whichhealth effects appear to have occurred in thiscountry are reported in studies of Buffaloand Nashville. The Buffalo study clearlyshows increased death rates from selectedcauses in males and females 50 to 69 yearsold at annual geometric means of 100 pg/maand over. The study suggests that increasedmortality may have been associated withresidence in areas with 2-year geometricmeans of 80 µg /ms to 100 pg/ms. The Nash-ville study suggests increased death ratesfor selected causes at levels above 1.1 cohs.Sulfur oxides pollution was also present dur-ing the periods studied. In neither studywere the smoking habits of the decedentsknown.
Corroborating information is suppliedfrom Fletcher's study of West London work-ers between the ages of 30 and 59. The dataindicate that with a decrease of smoke pollu-tion (yearly mean) from 140 pg /ma to 60pg/me, there was an associated decrease inmean sputum volume. Fletcher noted that
191183
there may have been changes in the tar com-position of cigarettes during the period stud-ied; such a change could affect the findings.This study provides one of the rare oppor-tunities to examine the apparent improve-ment in health that followed an improvementin the quality of the air.
3. Effects on Climate Near the GroundParticles suspended in the air scatter and
absorb sunlight, reducing the amount of solarenergy reaching the earth, producing hazes,and reducing visibility. Suspended particu-late matter plays a significant role in bring-ing about precipitation, and there is someevidence that rainfall in cities has increasedas the cities have developed industrially.
Suspended particulate matter, in the con-centrations routinely found in urban areas,considerably reduces the transmission ofsolar radiation to the ground, creating anincreased demand for artificial light. Theeffect is more pronounced in the winter thanin the summer, when particulate pollutionloadings are higher, and sunlight must pene-trate more air to reach the ground. Forsimilar reasons the effect is also more pro-nounced during the workweek than on week-ends, during industrial booms, and in higherlatitudes. For a typical urban area in theUnited States, with a geometric mean annualparticulate concentration of roughly 100ag/m3, the total sunlight, including that re-ceived directly from the sun and that reflect-ed by the sky, is reduced five percent forevery doubling of particle concentration. Thereduction is most pronounced on ultravioletradiation.
For urban areas in the middle and highlatitudes, particulate air pollution may re-duce direct sunlight by as much as one-thirdin the summer and as much as two-thirds inthe winter. This effect may have implica-tions for tha delicate heat balance of theearth's atmospheric system. In spite of anincrease in the carbon dioxide content of theatmosphere over the past several decades,which would presumably bring about anincrease in atmospheric temperature, meanworldwide temperatures have been decreaseing since the 1940's. Increased reflection ofsolar radiation back to outer space; brought
184
about by increased concentrations of particu-late air pollution, may be more than cancel-ling out the climatic effect of the increasedcarbon dioxide. That worldwide particulateair pollution has been increasing is evidencedby the fact that in the United States and inother countries, turbidity, a phenomenonproduced by the. back-scattering of directsunlight by particles in the air, has increasedsignificantly over the last several decades.
4. Effects on VisibilityParticles suspended in the air reduce vis-
ibility, or visual range, by scattering andabsorbing light coming from both an objectand its background, thereby reducing thecontrast between them. Moreover, suspendedparticles scatter light into the line of sight,illuminating the air between, to further de-grade the contrast between an object and itsbackground.
The scattering of light into and out of theline of viewing by particles in the narrowrange of 0.1 14 to 1 14 in radius has the greatesteffect on visibility. Certain characteristics ofbehavior of these particles make it possibleto formulate a useful approximate relation-ship between visual range and concentrationsof particulate matter:
,- AX 103
G'where G'. particle concentration (µg /me),
L,= equivalent visual range, and.4A=1.22 for L, expressed in kilome-
0.61.5tent and 0.750.38
for L, expressed in miles
The value 1.2 for A is the mid-range valueempirically obtained from observations in avariety of air pollution situations. The dataindicate that the range 0.6 to 2.4 coversvirtually all cases studied. The relationshipdoes not hold at relative humidities above 70percent, nor does it apply to fresh plumesfrom stacks, and it may not hold for theproducts of photochemical reactions. A com-panion document, Air. Quality Criteria ForSulfur Oxides, discusses a relationship be-tween levels of sulfur dioxide and visualrange at various relative humidities.
492-'
Within the limitations prescribed, the re-lationship provides a useful means of esti-mating approximate visual range from par-ticulate concentrations. In addition to aesthe-tic degradation of the environment, reducedvisibility has serious implications for safeoperation of aircraft and motor vehicles. Ata visual range of less than 5 miles, opera-tions are slowed at airports because of theneed to maintain larger distances betweenaircraft. Federal Aviation Administrationrestrictions on aircraft operations becomeincreasingly severe as the visual range de-creases below 5 miles. Using the upper andlower bounds of the relationship describedabove, visibility could be 5 miles at a par-ticulate loading as high as 300 µg /m3 or aslow as 75 µg /m3. However, on the average,visibility can be expected to be reduced toapproximately 5 miles at a particulate con-centration of 150 µg /m3. At a level of 100',terns, visibility is reduced to 71/a miles. Thislimited distance, however, may be related toparticulate concentrations as low as 50 fig/m3and as high as 200 µg /m3.
5. Effects on Materials
Particulate air pollution causes a widerange of damage to materials. Particulatematter may chemically attack materialsthrough its own instrinsic corrosivity, orthrough the corrosivity of substances absorb-ed or adsorbed on it. Merely by soiling ma-terials, and thereby causing their more fre-quent cleaning, particulates can acceleratedeterioration.
Laboratory and field studies underscorethe importance of the combination of par-ticulate matter and corrosive gases in thedeterioration of materials. On the basis ofpresent knowledge, it is difficult to evaluateprecisely the relative contribution of each ofthe two classes of pollution; however, somegeneral conclusions may be drawn.
Particulates play a role in the corrosion ofmetals. In laboratory studies, steel testpanels that were dusted with a number ofactive hygroscopic particles commonly foundin the atmosphere corroded even in cleanair. Corrosion rates were low below a rela-tive humidity of 70 percent; they increased
at relative humidities above 70 percent; andthey greatly increased when traces of sulfurdioxide were added to the laboratory air.
It is apparent that the accelerated corro-sion rates of variomanetals in urban andindustrial atmospheres are largely the re-sult of relatively higher levels of particulatePollution and sulfur oxides pollution. Highhumidity and temperature also play an im-portant synergistic part in this corrosion re-action. Studies show increased corrosionrates in industrial areas where air pollutionlevels, including sulfur oxides and particu-lates, are higher. Further, corrosion ratesare higher during the fall and winter sea-sons when particulate and sulfur oxides pol-lution is more severe, due to a greater con-sumption of fuel for heating.
Steel samples corroded 3.1 times faster inthe spring of the year in New York City,where annual particulate *concentrationsaverage 176 µg /m3, than did similar samplesin State College, Pennsylvania, where theaverage concentrations were estimated torange from 60 pg/m3 to 65 µg /m3. In thefall of the year, when particulate and sulfuroxide concentrations in New York were con-siderably higher than in the spring, the steelsamples in New York corroded six timesfaster than the samples at State College.Similar findings were reported for zincsamples. Moisture may have contributed tothe corrosion.
In Chicago and St. Louis, steel panels wereexposed at a number' of sites, and measure-ments taken of corrosion rates and of levelsof sulfur dioxide and particulates. In St.Louis, except for one exceptionally pollutedsite, corrosion losses correlated well with sul-fur dioxide levels, averaging 30 percent to80 percent higher than losses measured innonurban locations. Sulfation rates in St.Louis, measured by lead peroxide candle, alsocorrelated well with weight loss due tocorrosion. Measurements of dustfall in St.Louis, however, did not correlate significant-ly with corrosion rates. Over a 12-monthperiod in Chicago, the corrosion rate at themost corrosive site (mean SO2 level of 0.12ppm) was about 50 percent higher than atthe least corrosive site (mean SO2 level of0.03 ppm). Although suspended particulate
185
levels measured in Chicago with high-volumesamplers also correlated with corrosion rates,a covariance analysis indicated that sulfurdioxide concentrations were the dominantinfluence on corrosion. Based on these data,it appears that considerable corrosion maytake place (i.e., from 11 percent to 17 per-cent weight loss in steel panels) at annualaverage sulfur dioxide concentrations in therange of 0.03 ppm to 0.12 ppm, and althoughhigh particulate levels tend to accompanyhigh sulfur dioxide levels, the sulfur dioxideconcentration appears to have the moreimportant influence.
Particulate air pollution damages electri-cal equipment of all kinds. Oily or tarry par-ticles, commonly found in urban and indus-trial areas, contribute to the corrosion andfailure of electrical contacts and connectors.Dusts can interfere with contact closure, andcan abrade contact surfaces. Hygroscopicdusts will absorb water and forin thin elec-trolytic films which are corrosive.
Particulates soil and damage buildings,statuary, and other surfaces. The effects areespecially severe in urban areas where largequantities of coal and sulfur-bearing fueloils are burned. Partii;les may act as reser-voirs of acids, and thereby sustain a chemicalattack that will deteriorate even the moreresistant kinds of masonary. Particles stickto surfaces, forming a film of tarry soot andgrit which oftentimes is not washed away byrain. Considerable money and effort havebeen spent in many cities to sandblast thesooty layers that accumulate on buildings.Water-soluble salts, commonly found in ur-ban atmospheres, can blister paint. Otherparticles may settle on newly painted sur-faces, causing imperfections, thereby in-creasing the frequency with which a surfacemust be painted.
The soiling of textiles by the deposition ofdust and soot on fabric fibers not only makesthem unattractive, and thereby diminishestheir use, but results in abrasive wear of thefabric when it is cleaned. Vegetable fibers,such as cotton and linen, and syntheti' nylonsare particularly susceptible to chemical at-tack by acid components of airborneparticles.
186
6. Economic Effects of AtmosphericParticulate Matter
It is not possible at the present stage ofknowledge to provide accurate measures ofall the costs imposed on society by particu-late air pollution. Selected categories ofeffects can be quantified; it is obvious thatthese estimates represent a significant under-statement of the total cost.
7. Effects on Vegetation
Relatively little research- has been carriedout on the effects of particulate air pollutionon vegetation, and much of the work thathas been performed has dealt with specificdusts, rather than the conglomerate mixturenormally encountered in the atmosphere.This document reports briefly on some ofthese specific particulate studies only to illus-trate the possible mechanisms through whichparticulate matter may affect vegetation.This information is not presented for thepurpose of establishing air quality standardson these specific pollutants.
There is considerable evidence thatcement-kiln dusts can damage plants. Amarked reduction in the growth of poplartrees 1 mile from a cement plant was observ-ed after cement production was more thandoubled. Plugging of stomates by the dustmay have prevented the exchange of gasesin leaf tissue that is necessary for growthand development. Moderate damage to beanplants occurred when the plant leaves weredusted at the rate of 0.47 mg /cm= -day (400tons /m=- month) for 2 days and then exposedto natural dew. The mechanism throughwhich the leaves are damaged is not en-tirely understood, but direct alkaline dam-age to tissues beneath the crust formed bythe dust and moisture has been observed. Thedeposits may also plug stomates and blocklight needed for photosynthesis. Cement-kiln dusts may change the alkalinity of soilsto benefit or harm vegetation, depending onthe species.
Dust deposits may also eliminate preda-tors, and thereby bring on increased insectinjury to plants; they may interefere withpollen germination; and they may makeplants more susceptible to pathogens.
,1194
Fluoride dusts apparently have a difficulttime penetrating leaf tissue in physiologi-cally active form, and they are much less dam-aging to vegetation than is gaseous fluoride.Soluble fluoride dusts may be absorbed bythe plant, but the amount is relatively smallcompared to that which can enter the plantin gaseous form. The evidence suggests thatthere is little effect on vegetation at fluorideparticulate concentrations below 2 pg/m3.Concentrations of this magnitude and abovecan sometimes be found in the immediatevicinity of sources of fluoride particulatepollution; they are rarely found in urbanatmospheres.
Ingestion of particles deposited on plantscan be harmful to animal health. Fluorosisand arsenic poisoning have been brought onthrough this medium.
Soot may clog stomates and may producenecrotic spotting if it carries with it a solubletoxicant, such as one with excess acidity.Magnesium oxidedeposits on soils have beenshown to reduce plant growth, while ironoxide deposits on soils have been shown toreduce plant growth, while iron oxide de-posits appear to have no harmful effects, andmay be beneficial.
8. Effects on Public ConcernSeveral studies indicate that there is a
relationship between levels of particulatepollution, used as an index of air pollution,and levels of public concern over the prob-lem. A study conducted in 1963 in the St.Louis metropolitan region found a directlinear relationship between the fraction ofa community's population who said air pollu-tion was a nuisance, and the annual meanconcentration of particulate air pollution inthe community. The relationship, which wasderived from data on communities in the St.Louis area whose annual concentrationsranged from 50 µg /m3 to 200 µg /m3, wasformulated as:
y=0.3x 14where y= population fraction (%)
concerned, andx=annual geometric mean par-
tide concentration (pg/m2).
It is thought that the reaction to suspendedparticulates as a nuisance probably occursat peak concentrations, and not necessarilyat the values representing annual means.However, the relationship provides a usefulexample of how the nuisance effect of airpollution relates to concentrations. Approxi-mately 10 percent of the study populationconsidered air pollution a nuisance in areaswith suspended particulates at an annualgeometric mean concentration of 80 µg /m3.At this same level of pollution, 30 percent ofthe study' population was "aware of" airpollution. In areas with 120 1&g/m3 (annualgeometric mean), 20 percent were "botheredby" and 50 percent were "aware of" air pol-lution; in areas with an annual geometricmean of 16f, µg /m3, one-third of the popula-tion interviewed were "bothered by" andthree-fourths were "aware of" air pollution.
Although data from other studies do notreadily lend themselves to quantitative for-mulation, they do, in general, support therelationship reported by the St. Louis study.A study of communities in the Nashville,Tennessee, metropolitan area in 1957 foundthat at least 10 percent of the population ex-pressed concern about the nuisance of stirpollution at dustfall levels exceeding 10 tons/mil- month.
9. Suspended Particles as a Sourcesof Odor
Particulate air pollution is not ordinarilyconsidered a significant source of odors.However, there is evidence that liquid andeven solid particles of some substances maybe volatile enough to vaporize in the nasalcavity, and produce sufficient gaseous ma-terial to stimulate the sense of smell. Fur-ther, particles may carry absorbed odorantsinto the nasal cavity, and there transfer themto olfactory. receptors. A survey of State andlocal air pollution control officials revealedthat approximately one-fourth of the mostfrequently reported odors are those whichare known to be, or are suspected to be, asso-ciated with particulate air pollution. Thesources of these odorous particles are div-erse, including diesel and gasoline engineexhausts, coffee-roasting operations, paint
spraying, street paving, and the burning oftrash.
B. CONCLUSIONS
The conclusions which follow are derivedfrom a careful evaluation by the NationalAir Pollution Control Administration of theforeign and American studies cited in previ-ous chapters of this document. They repre-sent the Administration's best judgment ofthe effects that may occur when variouslevels of pollution are reached in the atmos-phere. The data from which Lie conclusionswere derived, and the qualifications whichshould be considered in using the data, areidentified by chapter reference in each case.
1. Effects on HealthAnalyses of numerous epidemiological
studies clearly indicate an association be-tween air pollution, as measured by particu-late matter accompanied by sulfur dioxide,and health effects of varying severity. Thisassociation is most firm for the short-termair pollution episodes.
There are probably no communities whichdo not contain individuals with impairedhealth who are particularly susceptible tothe adverse effects of elevated levels of par-ticulate matter and sulfur oxides. However,to show small changes in deaths associatedwith coincident higher levels of air pollutantsrequires extremely large populations. Insmall cities, these changes are difficult todetect statistically.
The epidemiologic studies concerned withincreased mortality also show increased mor-bidity. Again, increases in morbidity asmeasured, for example, by increases in hos-pital admissions or emergency clinic visits,are most easily demonstrated in major urbanareas.
For the large urban communities whichare routinely exposed to relatively high levelsof pollution, sound statistical analysis canshow with confidence the small changes indaily mortality which are associated withfluctuation in pollution concentrations. Suchanalysis has thus far been attempted onlyin London and in New York.
The association between longer-term cora-
188
munity exposures to particulate matter andrespiratory disease incidence and prevalencerates is conservatively believed to be inter-mediate in its reliability. Because of the re-enforcing nature of the studies conducted todate, the conclusions to be drawn from thistype of study can be characterized as prob-able.
The association between long-term resi-dence in a polluted area and chronic diseasemorbidity and mortality is somewhat moreconjectural. However, in the absence of otherexplanations, the findings of increased mor-bidity and of increased death rates for select-ed causes, independent of economic statusmust still be considered consequential.
Based on the above guidelines the follow-ing conclusions are listed in order.of reliabil-ity, with the more reliable conclusiiis first.Refer to Chapter 11 for cautions to be takenin comparing British and American air qual-ity measurement data.
a. AT CONCENTRATIONS OF 750µg /m' and higher for particulates on a 24-hour average, accompanied by sulfur dioxideconcentrations of 715 µg /m3 and higher,excess deaths and a considerable increase inillness may occur. (British data; see Chapter11, Section C-1)
b. A DECREASE FROM 140 µg /ms to 60WM' (annual mean) in particulate concen-trations may be accompanied by a decreasein mean sputum volume in industrial work-ers. (British data; see Chapter 11, SectionC-4)
c. IF CONCENTRATIONS ABOVE 300µg /m' for particulates persist on a 24-houraverage and are accompanied by sulfur diox-ide concentrations exceeding 630 µg /me overthe same average, period, chronic bronchitispatients will likely suffer acute worsening ofsymptoms. (British data; see Chapter 11,Section C-3)
d. AT CONCENTRATIONS OVER 200tig/mi for particulates on a 24-hour uverage,accompanied by concentrations of sulfurdioxide exceeding 250 µg /mm over the sameaverage period, increased absence of indus-trial workers due to illness may occur. (Brit-
is
ish data; see Chapter 11, Section C-5)e. WHERE CONCENTRATIONS RANGE
FROM 100 µg /m' to 130 p g / in, and above forparticulatei (annual mean) with sulfur di-oxide concentrations (annual mean) great-er than 120 p g/m3, children residing in suchareas are likely to experience increased inci-dence of certain respiratory' diseases.
f. AT CONCENTRATIONS ABOVE 100item' for particulates (annual geometricmean) with sulfation levels above 30 mg/cm2-mo., increased death rates for personsover 50 years of age are likely. (Americandata; see Chapter 11, Section C-2)
g. WHERE CONCENTRATIONS RANGEFROM 80 Item' to 100 p Wm' for particu-lates (annual geometric mean) with sulfa-tion levels of about 30 mg /cm= -mo., increaseddeath rates for persons over 50 years of agemay occur. (American data; see Chapter 11,Section C-2)
2. Effects on Direct SunlightAT CONCENTRATIONS RANGING
FROM 100 item' to 150 it Wm' for particu-lates, where large smoke turbidity fac orspersist, in middle and high latitudes directsunlight is reduced up to one-third in sum-mer and two-thirds in winter. (Americandata; see Chapter 2, Section C-2)
4. Effects on Materials
AT CONCENTRATIONS RANGINGFROM 60 p g/m3 (annual geometric mean),to 180 item' for particulates (annual geo-metric mean), in the presence of sulfur diox-ide and moisture, corrosion of steel and zincpanels occurs at an accelerated rate. (Amer-ican data; see Chapter 4, Section B)
5. Effects on Public ConcernAT CONCENTRATIONS OF APPROXI-
MATELY 70 pg/ms for particulates (annualgeometric mean), in the presence .of otherpollutants, public awareness and/or concernfor air pollution may become evident and in-crease proportionately up to and above con-centrations of 200 p g/m3 for particulates.(See Chapter 7, Section B-1)
C. RESUME
In addition to health considerations, theeconomic and aesthetic benefits to be obtain-ed from low ambient concentrations of par-ticulate matter as related to visibility, soiling,corrosion, and other effects should be con-sidered by organizations responsible forromulgating ambient air quality standards.
Under the conditions prevailing in areaswhere the studies were conducted, adversehealth effects were noted when the annualgeometric mean level of particulate matterexceeded 80 p g / . Visibility reduction toabout 5 miles was observed at 150 p g/m3, andadverse effects on materials were observed atan annual mean exceeding 60 p g/m3. It isreasonable and prudent to conclude that, whenpromulgating ambient air quality standards,consideration should be given to require-ments for margins of safety which take intoaccount long-term effects 'on health andmaterials occurring below the above levels.
3. Effects on Visibility
AT CONCENTRATIONS OF, ABOUT150 µg /m' for particulates, where the pre-:dominant particle size ranges from 0.2 N. to1.0 it and relative humidity is less than 70percent, visibility is reduced to as low as 5miles. (American data; see Chapter 3, Sec-tion E-4)
1.97189 Ne
A
Be
B
C
B.
I
Ie
P
APPENDIX ASYMBOLS
Brea of the filter stain, cm=
turbidity coefficient ( empirical ) , A = 0.5it
particle concentration in the air, µg /m3
turbidity coefficient, measured on theground
turbidity coefficient, measured at heightz above the ground
light intensity, usually in ergs/cm=fsec
initial or incident light intensity
equivalent visual range, or visibility, butcalculated on basis of a constant scat-tering coefficient, b, along the line ofsight
probabilityP (A)
solar transmission factor for atmos-phere aerosols; it is a function of A
particle mass concentration in the air,usually in µg /m2
scattering cross-section, cm= /particle
derived surface particle concentration,Sc
S
T
V
b
gi cm 2
transmissivity, I/Io
volume of air sampled, m3
extinction coefficient, m-3( =b+ b + b +b )
abs gas Rayleigh seat
192
abs aerosol
b
b
b
b
d
e
g
m
V
X
z
a
/3
A
X
abs aerosolextinction coefficient due
by aerosol particles
abs gasextinction coefficient due
by gas such as NO2
Rayleighextinction coefficient due
gas molecules
to absorption
to absorption
to scatter by
scatextinction coefficient due to scatter by
aerosols
diameter of a spherical particle, cm
Napierian log base ( =2: .82818)
acceleration of gravity, cm/sec=
index of refraction
correlation coefficient
settling velocity of a particle, cm/sec
distance, m or cm
height above ground, meters
light scattering coefficient (empirical)relates b to A
turbidity coefficient for A=144
viscosity of air, or other gas, poises
wavelength of light Angstroms, microns,or nanometers
probability function, usually expressedas x2 ("Chi square")
.1.891 I.
APPENDIX BABBREVIATIONS
A Angstrom, 1A =10 -6 cmBTPS body temperature, pressure,
saturatedcm centimeter, lcm = 10-2mcm= square centimetercm3 cubic centimeterCMD count median diametercoh coefficient of hazeDMBA ,10-dimethy1-1, 2 benzanthraceneFEV forced expiratory volumeFVC forced vital capacityg mass, gramshr -hour1 literm length, meter
m3mgmimi=minmlMMDmo
wgppmRUDSsecyr
200
cubic metermilligrammilesquare mileminutemillilitermass median diametermonthmillimicron, 0.001p,micron, 1p,= 10-4cm= 10-om = 104Amicrogramparts per millionreflectance unit of dirt shadesecondyear
a
193
To convertmg/msmg/100 m3µg /ft3pg/1000 m3itg S02 /m3
(0°C, 760 mm Hg)ppm SO2 (vol) SO2 aims (0° C, 760 mm Hg) 2860tons/mi2-mo mg/cm3-mo 3.5 x 10-2tons/mi2-mo g/m2-day 1.07 X 10-3tons/mi2-mo metric tons/km2 -mo 3.5 x 10-'tons/mi2-mo pg/m2-mo g.5 x 103mg/cm2-mo tons/mi2-mo 28.5g/m2-day tons/ref-mo 85.5p or pm m 10-414 A 104A cm 10-814 cm 10-4bbl gal. 551 ft3 C:i q1153ft3 1 28.32ml in' 6.1 x 102m ft 3.28lb g 453.6
APPENDIX C.- CONVERSION FACTORS
To Multiply byPerna 1000µg /m3 10pg/ms 35.314;terns 10-4
ppm SO2 (vol) 3.5 x 10-'
194
-201
1;1
APPENDIX D-- GLOSSARY
Acid, freean acid which is unneutralizedby other compounds
Acid, stearicthe most common fatty acidoccurring in natural animal and vegetablefats, almost completely colorless and odor-less
Acroleina toxic colorless mobile liquid al-dehyde with an acrid odor
Adenocarcinomaa malignant tumor inwhich the cells are arrar ged in the formof glands or gland-like structures
Adenomaan epithelial tumor, usually be-nign, with a gland-like structure
Adhesionthe attraction of two unlike sub-stances
Adsorptionthe phenomenon by which gasesare attracted, concentrated, and retainedat a boundary aid: face
Aerodynamicsa phase of the mechanics offluids, its study being limited to the re-actions caused by relative motion betweenfluid and solid, the fluid being limited toair in most cases but occasionally broad-ened to include any gas
Aerosola cloud of solid particles and/orliquid droplets smaller than 100p in di-ameter, suspended in a gas
Aerosol, bidispersean aerosol in which allthe suspended particles tend to be of twosizes (diameter)
Aerosol, monodispersean aerosol in whichall the suspended particles are of nearlyequal size (diameter)
Air, residualthe air that stays in the lungsafter forceful expiration
Air, tidalthe air that is carried to andfrom the lungs during a respiratory cycle
Airwayany part of the respiratory.tractthrough which air passes during breathing
Airway resistanceresistance to the flow ofair in the passages to the lungs
Albedothe ratio of the amount of electro-magnetic radiation reflected by a body tothe amount incident upon it, commonly ex-pressed as a percentage
Aldehydeany of a class of organic com-pounds containing the group R-CHO, in-termediate in state of oxidation betweenprimary alcohols and carboxylic acids
Alveolus (pl. alveoli)a small, sac-like dila-tion at the innermost end of the airway,through whose walls gaseous exchangetakes place
Analysis, factoriala method of evaluating'certain definite integrals by the use ofgamma functions
Anaplasia (adj. anaplastic)acondition intumor cells in which normal functional andphysical differentiation is lost
Anthracosisa disease of the lungs causedby inhalation and accumulation of carbon
particlesAntirachiticopposing or preventing the
development of ricketsAphid (aphis)a small sucking insect; a
plant louse
Atelectasisthe collapse of all or part of alung, with resultant loss of functioningtissue
Attenuation In physics, any process inwhich the flux density (or power, ampli-tude, intensity, illuminance, etc.) of a"parallel beam" of energy decreases withincreasing distance from the energy source
Auscultation (adj. Auscultatory)the act oflistening for sounds within the body, us-ually with the use of a stethoscope
Bacillus subtilika common microorganismfound in soil and water and frequently oc-curring as a laboratory contaminant; rare-ly implicated in causing disease
202195
Benzo (a) pyrenea polycyclic aromatic hy-drocarbon which under certain ecum-stances has been shown to produce cancer
Bifurcationa site where a single structuredivides into two branches
Blistering, osmoticpaint blisters caused bymoisture picking up water-soluble salts inits passage through the paint film, result-ing in an ideal situation for osmosis whichrepresents a tremendous force formationof blisters
Blo'vby the leakage of gas or liquid be-tween a piston and its cylinder during op-eration
Body, asbestosa fiber of asbestos sur-rounded by a deposit of protein material
Bronchiectasisa chronic dilatation of abronchial passage
Bronchioleone of the finer subdivisions ofthe bronchial tree
Bronchitisan inflammation of the bronchi,'usually manifest clinically by cough andthe production of sputum
Bronchitis, chronic--a long-standing inflam-mation of the bronchi characterized by ex-cessive mucus secretion in the bronchialtree and manifested by a persistent or re-current productive cough. For the pur-poses of definition, these symptoms mustbe present on most days for a minimum of3 months of the year for at least 2 suc-cessive years (American Thoracic Soci-ety)
Bronchoconstrictiona diminution in thesize of the lumen of a bronchus
Bronchus (pl. bronchi)one of the largerair passages in the lung
Brotha liquid medium for the cultivationof microorganisms
Capacity, forced vital (FVC)the largestamount of gas which can be forcibly ex-pired from the lungs following a maximalinspiration
Capacity, functional residual (FRC)thevolume of gas remaining in the lungs atthe resting end-expiratory level
Capacity, total lung (TLC)the volume ofgas contained in the lungs at full inspira-tion
196
Capacity, vitalthe maximum volume ofgas which can be expired from the lungsfollowing a maximum inspiration
Carbonationconversion into a carbonate(which in many cases refers to one ormore members of the calcite, dolomite, andaragonite groups of minerals) impregna-tion with carbon dioxide
Carcinogena substance capable of causingliving tissue to become cancerous
Carcinogenesisthe production of cancerCarcinomacancer; malignant growth made
up of cells derived from epithelial tissueCarcinomas bronchogeniccancer arising in
bronchial tissue of the lungCarcinoma, squamous cellscancer develop-
ing from squamous epithelial cellsCarcinoma in situa neoplastic entity in
which tumor cells are present but the in-vasion of normal tissue has not yet takenplace
Cardoivascularpertaining to the heart andblood vessels
Cercospora beticolaa member of the genusCercospora, which consists of imperfectfungi that are leaf parasites with longslender multi-septate spores
Channel blackcarbon black made by im-pingement of a luminous natural gas flameagainst an iron plate from which it isscraped at frequent intervals; propertiesvary widely, but the material has an un-usually fine state of subdivision and greatsurface area
Chloroplasta specialized body (a plastid)containing chlorophyll in the cytoplasm ofplants; the site of photosynthesis andstarch formation in plants
Cholinesteraseany one of several enzymesthat hydrolyze choline esters, occurringmost frequently in nervous tissue and theblood
Cilium (pl. cilia)small, hairlike process at-tached to a free surface of a cell, capableof rhythmic movement
C'earancethe removal of material fromthe body or from an organ
Clinkerkiln-fired limestone from whichcommercial cement is made
Coalescencein cloud physics, the mergingof two water drops into a single largerdrop
-903
Coefficient, absorptionthe fractional rateat which flux density of radiation decreasesby absorption with respect to the thick-ness of the absorbing medium traversed
Coefficient, extinctionthe sum of the ab-sorption coefficient and the scattering co-efficient for a medium that both absorbsand scatters radiation
Coefficient, scatteringthe fractional ratein the transmission of radiation through ascattering medium (as of light throughfog) at which the flux density of radia-tion decreases by scattering in respect tothe thickness of the medium traversed
Coh unita measure of light absorption byparticles, defined as that quantity of lightscattering solids producing an optical den-sity of 0.1
Collagen--a fibrous protein forming themain supportive structure of connectivetissue
Collector, cyclonica centrifugal fraction-ator in which a vortex of air thrcws par-ticles out of a stream, where they collector stick to the surface of a container
Comminuteto break or crush into smallpieces
Concentration- -the total mass (usually inmicrograms) of the suspended particlescontained in a unit volume (usually onecubic meter) at a given temperature andpressure; . sometimes, the concentrationmay be expressed in terms of total num-ber of particles in a unit volume (e.g.,parts per million) ; concentration mayalso be called the "loading" or the "level"of a substance concentration may also per-tain to the strength of a solution
Coniferbelonging to the coniferales order,consisting primarily of evergreen treesand shrubs
Consolidationthe process by which a dis-eased lung passes from an aerated col-lapsible state to one of an airless solidconsistency because of accummulation ofexudate
Contrastin visual range theory, the ratioof the apparent luminance of a target mi-nus that of its background to the apparentluminance of the background
Conurbationa great aggregation or con-tinuous network of urban communities
Coryzctan acute catarrhal conditiOn of thenasal mucous membrane with profuse dis-charge from the nostrils
Criteria, air qualitya compilation of thescientific knowledge of the relationship be-tween various concentrations of pollutantsin the air and their adverse effects
Cryolitea mineral fluoride consisting alsoof sodium and aluminum
Cuticlea varnish-like layer covering thesurface of a leaf
Cytoplasmthe protoplasm of a cell (ex-cluding that of the nucleus)
Dead space, anatomicthat part of the air-way occupied by gas which is unavail-able (by its location) to take part in oxy-gen-carbon dioxide exchange through thewalls of the alveoli
Dead space, physiologicthe volume of gaswithin the alveoli which does not partici-pate in the oxygen-carbon dioxide ex-change through the walls of the alveoli
Dehydrogenaseany one of various enzymeswhich accelerate the removal of hydrogenfrom metabolities and its transfer to othersubstances, thus playing an important rolein biological oxidation-reduction processes
Deliquesceto dissolve gradually and be-come liquid by absorbing moisture fromthe air
Densitythe amount of matter per unit vol-ume, usually expressed in grams per cubiccentimeter
Density, opticalthe degree of opacity ofany translucent medium; the common loga-rithm of the ratio of the initial intensityof light to the intensity of transmitted orreflected light
Desorptionthe release of a substance whichhas been taken into another substance bya physical process or held in concentratedform upon the surface of another sub-stance; the reverse of absorption or ad-sorption
Desquamateto cast off epidermis in shredsor scales; to peel off in sheets or scales
Deviation, standard geometric (og) ameasure of dispersion of values about ageometric mean; the portion of the fre-quency distribution that is one standardgeometric deviation to either side of the
197
geometric mean accounts for 68% of thetotal samples
Deviation, standard nor mala measure ofdispersion of values about a mean value;the square root of the average of thesquares of the individual deviations fromthe mean
Dextrana water-soluble polymer usedtherapeutically as a plasma substitute
Diameter, count median (CMD)the geo-metric median size of a distribution ofparticles, based on a numerical count
Diameter, mass median (MMD)the geo-metric median size of a distribution of par-ticles, based upon a weight (usually de-rived from a Stokes' Diaineter)
Diameter, Stokes'the diameter that a unitdensity particle of spherical shape wouldhave if it behaved the same as the particlebeing studied
Dichotomousdividing in succession intopairs; showing a dual arrangement
Distalfurthest or most remote from themedian line of the body, from the pointof attachment, or from the origin; periph-eral (cf. proximal)
Diverticulum (pl. diverticula)a pouch orcul-de-sac of a hollow organ
Dosimetrythe accurate measurement anddetermination of (medicinal) doses
Dyspneadifficult or labored breathingEarth, diatomaceousa chalky material used
as a filter aid, an absorbent, a filler, anabrasive, and as thermal insulation
Edemaa condition due to the presence ofabnormally large amounts of fluid in theintercellular tissue spaces of the body
Effluentsomething that flows out, such asa liquid discharged as a waste
Elutionthe process of washing out, or re-moving with the use of a solvent
Elutriator, fractionala tractional samplerwhich removes coarse particles from theair by gravity settlement
Emphysemaa swelling due to the presenceof air, usually excess or additional air.The term is usually used to refer to pul-monary emphysema
Emphysema, pulmonarya condition inwhich there is overdistension of air spacesand resultant destruction of alveoli andloss of functioning lung tissue
198
Endocytosisa condition or disease arisingfrom the inclusion within a cell of ma-terial which does not properly belong there
Entomologyzoology dealing only with in-sects
Epidemiologya science dealing with thefactors. involved in the distribution andfrequency of a disease process in a popu-lation
Epidermisthe outermost layer of skin inanimals; any integument
Epiglottisa plate of cartilage which coversthe entrance to the larynx during swal-lowing, thus preventing food or fluid fromentering the windpipe
Epithelium--a closely packed sheet of cellsarranged in one or more layers, coveringthe surface of the body and lining holloworgans
Epithelium, columnara type of epitheliumcomposed of tall, prismlike cells
Epithelium, spuamousa type of epitheliumcomposed of plate-like cells
Ergometeran instrument which measureswork done, e.g., by muscle contraction; adynamometer
Evaginateto turn inside out or protrudeby eversion
Extrapolateto project data into an areanot known or experienced, and arrive atknowledge based on inferences of conti-nuity of the data
Fibrosisthe development of fibros tissue;sclerosis
Filiformhaving the shape of a thread orfilament
Flocsomething occurring in indefinitemasses or aggregates
Fluorosisa pathologic condition resultingfrom excessive intake of fluorine
Fluorsparthe mineral fluoriteFluxa flowing or discharge of fluid; a sub-
stance used to promote fusion (as by re-moving impurities) of metals or minerals;the rate of transfer of fluid, particles, orenergy (as radiant energy) across a givensurface
Fumean aerosol formed by the condensa-tion of vapors as they cool
Gastricpertaining to the stomachGastrointestinalpertaining to the stomach
and intestines
Goblet cella type of epithelial cell contain-ing mucus and having the shape of a flaskor goblet
Gravimetricof or relating to measurementby weight
Hazefine dust or salt particles dispersedthrough a portion of the atmosphere; theparticles are so small that they cannot befelt or individually seen with the nakedeye, but they diminish horizontal visibil-ity and give the atmosphere a character-istic opalescent appearance that subduesall colors
Hematitethe mineral iron oxide; Fe203Histaminea substance which produces di-
latation of capillaries and stimulates gas-tric secretion, occurring in both animal andvegetable tissues; p-imidazolethylamine
Histograma graphical representation us-ing a series of bars
Histologythe study of the anatomy of tis-sues and their microscopic cellular struc-ture
Hydrocarbona compound containing onlyhydrogen and carbon. This group is sub-divided into alicyclic, aliphatic, and aro-matic hydrocarbons according to the ar-rangement of the atoms and the chemicalproperties of the compounds.
Hygroscopicreadily absorbing and retain-ing moisture from the atmosphere
Hyperplasia (adj. hyperplastic)an in-crease in the number of cells in and bulkof a tissue, with retention in normal func-tion and cellular structure
Illuminationthe process in which light isbrought to some surface or object
Impactor, cascadean instrument whichemploys several impactions in series tocollect successively smaller sizes of par-ticles
Incidencethe rate at which a certain eventor disease occurs
Insolation the rate at which direct solar ra-diation (of all wavelengths) is deliveredto a unit area of a horizontal surface, us-ually at or near ground level
Insulationthe prevention of the transferof energy between two conductors by sepa-ration of the conductors with a non-con-ducting material; or, the non-conductingmaterial itself
4 I, a.
Interstitialpertaining to or situated in thespace between cells
In vitroin a test tube or other artificialenvironment
In vivowithin a living bodyIsotherma line on a chart representing
changes of volume or pressure under con-ditions of .constant temperature; or lineson a map connecting points having thesame temperature
Ketoneany of a class of organic compoundsthat are characterized by a carbonyl groupattached to two carbon atoms, usually con-tained in hydrocarbon radicals or in asingle bivalent radical, similar to alde-hydes but less reactive
Lacrimation (lachrymation)tear forma-tion, especially in excess
Langleya unit of energy per unit area,commonly employed in radiation theoryand equal to one gram-calorie per squarecentimeter
Larynxthe organ concerned with the pro-duction of the voice, situated at the upperend of the trachea
Lesionan injury or other circumscribedpathologic change in a tissue
Logarithma number which represents thepower to which a given number must beraised to produce another given number
Lumenthe inner space of a hollow organor tube
L7copodiuma genus of club-moss; a pow-der ("vegetable sulfur") used to preventthe agglutination of pills in a box or asa dusting powder
Lympha fluid that is collected from thetissues throughout the body, flows in thelymphatic vessels, and is eventually addedto the bloodstream
Lymphomaany neoplasm developing fromlymphatic tissue
Macrophagea large phagocytic cell foundin the connective tissue, especially in areasof inflammation
Malignancysomething which tends to be-come progressively worse and if un-checked could result in death
Mastoiditisan inflammation of the skullbone behind the ear
Mean, geometric (M.)a measure of cen-tral tendency for a log-normal distribution;1)
199
the value, in a given set of samples, aboveINNich 50% of the values lie
Meatusa natural body passage, particular-ly the external opening of a canal
Mesotheliomaa tumor which develops fromthe lining of a coelomic body cavity
Metaplasia (adj. metaplastic)a change inthe cells of a tissue to a form which is notnormal for that tissue
Metastablemarked only by a slight marginof stability
Meteorological range (standard visibility,standard visual range)an empiricallyconsistent measure of the visual range ofa target; a concept developed to eliminatefrom consideration the threshold contrastand adaptation luminance, both of whichvary from observer to observer
Morbiditythe occurrence of a disease stateMorphologya branch of biology dealing
with the structure and form of living or-ganisms
Mortalitythe ratio of the total number ofdeaths to the total population, or the ratioof the number of deaths from a given dis-ease to the total number of people havingthat disease
Motion, Brownianthe rapid random mo-tion of small particles due to bombard-ment by surrounding molecules which arein thermal motion
Mucina glycoprotein or mucopolysaccha-ride secreted by mucous glandular cells
Mucopurulentpertaining to an exudate (orsputum) that is chiefly purulent (pus) butalso contains significant amounts of mucus
Mucoviscidosiscystic fibrosisMucus (adj. mucous)the clear viscid se-
cretion of a mucous membraneMuratpertaining to the wall of a cavityMustard gasan irritating and toxic volatile
liquid used as a weapon in World War 1;dichloroethyl sulfide
Naris (pl. nares)a nostril or other open-ing into the nasal cavity
Nasopharynx the part of the pharynx(throat) lying above the level of the softpalate
Nebulizeto reduce to a fine sprayNecrosisloatlized death of cellsNeoplasm any abnormal growth, such as
a tumor
200
Nephelometera photometric instrumentfor the determination of the amount oflight transmitted or scattered by a sus-pension of particles
Nodea circumscribed swellingNode, lymphone of many accumulations of
lymphatic tissue situated throughout thebody
Nomograma graph that enables one toread off the value of a dependent variablewith the use of a straightedge, when thevalues of two or more independent vari-ables are known
Nucleationthe process of particle growththrough collection around a nucleus
Nucleus (condensation nucleus)a particlein the size range from 0.1p to 1p whichserves as a nidus on which water or othervapors in the air can condense to formliquid droplets
Olefin --a class of unsaturated aliphatic hy-Arocarbons of the general formula C.11.
Olfactorypertaining to the sense of smellOphthalmicpertaining to the eyeOtitisan inflammation of the earPalisade tissuea layer of columnar cells
rich in chloroplasts found beneath the up-per epidermis of foliage leaves
Parameteran arbitrary constant whichcharacterizes a mathematical expression
Parenchymathe specific or functional tis-sue of a gland or organ, as opposed to itssupporting framework
Particleany dispersed matter, solid or liq-uid, in which the individual aggregatesare larger than single small molecules(about 0.0002p in diameter), but smallerthan about 500p in diameter
Particulateexisting in the form of minuteseparate particles
Pathogenesisthe production or the modeof origin and development of a diseasecondition
Pathologythe study of the essential natureof disease, particularly with respect to thestructural and functional changes in or-gans and tissues
Peritoneum-the membrane lining the ab-dominal cavity and investing the viscera
Phagocytea cell that has the power of in-gesting microorganisms and other smallparticles
Phagocytosis the ingestion of a microor-ganism or other small particle by a phago-cyte
Pharynxthe upper expanded portion of thealimentary canal lying between the mouth,the nasal cavities, and the beginning ofthe esophagus; the throat
Photometeran instrument for measuringluminous intensity, luminous flux, illumi-nation, or brightness by comparison of twounequal lights from different sources
Photomicrographa photograph of a mag-nified image of a small object
Photosynthesisthe formation of carbohyrdrate from carbon dioxide and water inthe presence of chlorophyll and light, inplant tissues
Physiologya science which studies thefunction of a living organism or its parts
Phytotoxicharmful to plant materialsPlasmolysi:tthe shrinking of the cytoplasm
away from the wall of a living cell due towater loss by osmotic action
Plethysmographan apparatus for the de-termination and recording of a change inthe size of an organ or limb or body
Pneumococcus (pl. pneumococci)a bacte-rial organism which most often infects thelung and is a common cause of pneumonia;Diplococcus pneumoniae
Ptieumoconiosisa fibrous reaction in thelungs, caused by the retention of certaininhaled dusts in the lungs
Pneumonitis a general term for inflamma-tion of the lung
Pneumotachygraphan instrument used todetermine the force and velocity of re-spired air
Polystyrenea clear, colorless polymer ofstyrene, an unsaturated hydrocarbon ofthe form C6115CH=C11,
Potentiationsynergism, as between twoagents which together have a greater ef-fect than the sum of their effects whenacting_ separately
Precipitationany or all of the forms ofwater particles, whether liquid or solid,that fall from the atmosphere and reachthe ground. It is a major class of hydro-meteor, but is distinguiPhed from cloud,fog, dew, rime, frost, etc. in that it must"fall," and is also distinguished from cloud
and virga in that it must reach the groundPrecipitator, electrostatican apparatus for
the removal of suspended particles froma gas by charging the particles and pre-cipitating them by applying a strong elec-tric field
Predatoran organism living by preying onother organisms
Prevalencethe number of cases of a dis-ease at a given time
Prodromethe symptoms preceding the ap-pearance or recognition of an actual dis-ease state
Proteinosisthe accumulation of protein inexcess in the tissues
Proteinosis, alveolara chronic progressivelung disease characterized by the accumu-lation of granular proteinaceous materialin the alveoli
Proximalnearest to the center of the bodyor the point of origin (cf. distal)
Radioautograph (autoradiogram)a radio-graphic portrayal of an object or organismmade by the inherent radioactivity of theobject or organism
Ralean abnormal respiratory sound heardin auscultation of the chest
Ratio, standardized mortalitythe ratio ofthe number of deaths observed in a givenpopulation over a given period of time tothe number of deaths expected to occurin the given population over the same pe-riod of time if the given population be-hayed as any other group of similar com-position would during that same period
Reflectometera photometric or electronicdevice for ineasuring the reflectances oflight or other radiant energy
Regressiona trend or shift toward a mean.A regression curve or line is thus one thatbest fits a particular set of data accordingto some principle
Rhinitisan inflammation of the nasal mu-cous membrane
Rhinorrhea . "runny nose"Rhonchus (pl. rhonchi)a dry, coarse sound
usually originating from partial obstruc-tion in a bronchial tube
Scattering, Mieany scattering produced byspherical particles, without specific regardto the comparative size of radiation wave-length or particle diameter
'1: 208 201
Scattering, Rayleighany scattering proc-ess produced by spherical particles whoseradii are smaller than about one-tenth thewavelength of the scattered radiation
Sigmoid curvea "bell-shaped" curve serv-ing as a prototype for the normal distri-bution of data about a mean
Silicosisa type of pneumoconiosis causedby inhalation of silica dust and character-ized by silica-containing nodules of scartissue in the lung parenchyma
Sorptionthe generalized term for the manyphenomena commonly included under theterms adsorption and absorption, when thenature of the phenomenon is unknown orindefinite
Spirometeran instrument for the measure-ment of the volume of gas respired by thelungs
Sporea reproductive element of manylower organisms
Squamous resembling or covered withscales
Standards, air quality levels of air pollut-ants which cannot legally be exceeded dur-ing a specific time in a specific geographi-cal area
Stasisthe slowing down or cessation of thenormal flow
Stigmathe part of the pistil of a flowerwhich receives the pollen granules and onwhich they germinate
Stokes' Lawa law in physics stating thatthe force required to move a spherethrough a given viscous fluid at a low uni-form velocity is directly proportional tothe velocity and radius of the sphere
Stoma (pl. stomata) tea small opening in theepidermis of a plant
Subcutaneousbeneath the skinSupercool to cool below the freezing point
without solidification or crystallizationSupersaturation-- a condition of containing
an excess of some material or force, overthe amount required for saturation nor-mally
Synergisma situation in which the com-bined action of two or more agents actingtogether is greater than the sum of theaction of these agents separately
Systemicrelating to the body as a whole,rather than to its individual parts
202
Tanninany one of a group of soluble as-tringent complex phenolic substances thatare widely distributed in plants
Terpeneany one of a class of isomeric hy-drocarbons of the prototype Colin thatare found in many essential oils, but espe-cially from conifers; may also refer to anyof various compounds derived from ter-pene hydrocarbons or closely related tothem
Tipburna disease of the potato, lettuce, andother cultivated plants, characterized byburning or browning of the tips and mar-gins of the leaflets and caused by loss ofwater due to excessive heat and sunshine
Toxicologythe study of poisons, includingtheir preparation, identification, physio-logic action, and antidotes
Tracheawindpipe; the airway extendingfrom the larynx to the origin of the twomainstem bronchi
Tracheobronchitisan inflammation of thetrachea and bronchi
Turbidityin meteorology, any condition inthe atmosphere which reduces its trans-parency to radiation, especially to visibleradiation
Tyndallometeran instrument that meas-ures suspended particle concentration bythe amount of light scattered out of abeam
Uttrafitterabiecapable of being separatedby a dense filter which is used for thefiltration of a colloidal solution holdingback the dispersed particles but not theliquid
Updraftan upward movement of air orother gas
Ventilation, minutethe total volume of gasrespired in one minute, i.e., the tidal vol-ume multiplied by breaths per minute
VisibilityIn United States weather observ-ing practice, the greatest distance in agiven direction at which it is just possibleto see and identify with the unaided eye(a) in the daytime, a prominent dark ob-ject against the sky at the horizon, and(b) at night, a known, preferably unfo-cused, moderately intense light sourea.After visibilities have been determinedaround the entire horizon circle, they are
--209
resolved into a single value of prevailingvisibility for reporting purposes.
Visual rangethe distance, under daylightconditions, at which the apparent contrastbetween the specified type of target andits background becomes just equal to thethreshold contrast of an observer; to bedistinguished from the night visual range.The visual range is a function of the at-mospheric extinction coefficient, the albe-do and visual angle of the target, and the
observer's threshold contrast at the mo-ment of observation.
Volume, forced expiratory (FEV)the vol-ume of gas forcibly exhaled over a giventime interval (usualtj, measured in sec-onds) after maximum inspiration, e.g.,FEV1.0 for this mecsurement over a 1.0second period.
Volume, minutesame as minute ventilationVolume, tidatthe volume of gas inspired or
expired during each respiratory cycle.
Ackley, C., 94Agnese, G., 162, 172-173Ahlquist, N. C., 56, 57, 59Albert, R. E., 122Alcocer, A. E., 26Altshuler, B., 113, 117, 118Amberg, H. R., 106Amdur, M. 0., 113, 131, 132, 133,
134, 136Andersen, A. A., 17, 19Anderson, D. 0., 150, 161, 104, 165,
173-174Anderson, P. J., 92Andrea, J., 140Angel, J. H., 168, 175Angstrom, A. K., 38, 39, 43, 53Antler, M., 69Antweiler, H., 121Arnett, L. C., 122Ashworth, J. R., 41, 44Auerbach, 0., 141Axt, C. J., 19Ayer, H. E., 137
Baetjer, A. M., 132Balzer, J. L., 137Barfinkel, L., 141Barlett, F. E., 106Bates, D. V., 163,173 -174Baulch, D. M., 19, 37Baumberger, J. P., 117Bechmann, H., 117Becker, W. IL, 165, 173-174Belton, J., 154Berge, H., 94Biersteker, K., 168, 176Black, S., 118Blifford, I. H., 11Bohne, IL, 91, 92, 94Bonser, G. M., 139Boren, H. C., 135Bowden, A. T., 26Bownes, K., 105Bradley, W.. 152, 154, 156, 171, 172Brandt, P., 17Brasser, L. J., 150, 153, 158Braverman, M. M., 153, 154, 171Brieger, H., 122Brier, G. W., 41Briscoe, W., 122Brooke, A. G. F., 71Brown, C. E., 117Brown, D. A., 157,172
204
AUTHOR INDEX
Brown, J. H., 118Brown, M. C., 137Bryson, R. A., 42, 43Buck, S. F., 157, 172Bunyard, F. L., 99Burgess, F., 130, 131, 136Burgess, S. E., 151, 171Burn, J. L., 157, 158, 159, 164, 172-
173, 174Bye, W. E., 167
Cadle, R. D., 8, 10Cambell, J. A., 137Capps, R., 135Carey, W. F., 69Carnes, W. H., 141Cartwright, J., 69, 71Casarett, L. J., 122, 123Cassel, E. G., 150, 154, 156, 171, 172Cefis, F., 139Chaney, A. L., 26Changnon, S. A., Jr., 41Charlson, R. J., 19, 54, 55, 56, 57, 59Chass, R. L., 24Christofano, E. E., 135, 136Clark, J. G., 22Clark, W. E., 23, 54Clemo, G. R., 137Coblentz, H., 39Coffin, D. L., 129Collet, A., 123Collins, G. F., 106Conner, W. D., 53Cook, K. M., 118Cooley, R. N., 132Cooper, W. C., 137Copson, H. R.-. 66, 67, 68, 69Corn, M., 6, 8, 19, 132, 133Conghanower, D. R., 136Cralley, L. J., 137Creasia, D. A., 133Crider, W. L., 26Crowley, D., 154, 155Cuffe, S. T., 5Cullumbine, H., 130, 132, 136Czaja, A. T., 91, 92
Dalhamn, T., 121, 122, 135Darley, E. F., 90, 91, 92, 93Dantrebande, L., 117, 119, 133, 135Davies, C. N., 111, 117, 118, 119,
121, 122, 123, 132, 135, 136Davies, R. I., 157, 171-172
Day, J. A., 11De Groot, I., 99, 101Deily, J, G., 18De Maio, L., 19Dennis, W. L., 118Dessens, J., 18De Treville, R. T., 135Devir, S. E., 131Diamond, J. R., 149, 155, 156, 171,
172Dickerson, R. C., 20, 22Diem, M., 17Djordjevic, N., 11Dobrogorski, 0. J., 130Dohan, F. C., 164Doherty, R. E., 26Douglas, J. W. B., 165, 173-174Downs, W. L., 122Draftz, R. G., 18Draper, P., 26Drinker, P., 8, 113, 117, 118, 132Drolette, B. M., 153, 154, 171Du Bois, A. D., 133
Eckel, 0., 39Edmonds, S. M., 106Elliott, A., 166Ellis, 0. B., 66, 67, 68Ellison, J. M., 22Epstein, S. S., 140Erdhardt, C., 153, 154, 171
Falk, H. L., 120, 134, 137, 138, 141Faoro, R. B., 16Faulds, J. S., 139Fensterstock, J. C., 16Ferris, B. G., Jr., 164, 173-174Field, F., 153, 154, 171Fieldner, A. C., 117Findeisen, W., 114, 115, 119Finn, J. L, 117Firket, J., 150Fischer, W. H., 19Fish, B. R., 10Fisher, M., 121Flesch, J., 132Fletcher, C. M., 168, 175Fochtman, E. C., 71Foster, K. E., 17Frank, E. R., 20, 23Frederick, R. H., 41Friedlander, S. K., 54, 58
Gates, D. M., 38Georgii, H. W., 41Gibb, F. R., 117, 119, 121Gilbert, J., 69Giles, C. H., 69Gincr, R., 40Girorer, W., 117Glasser, M., 154, 155Goetz, A., 6, 10, 19, 58, 59,106Gong, W. K., 26Gore, A. T., 151, 171Graf, P., 132Graff-Baker, C., 71Greenburg, L., 68, 69, 153, 154, 171Greenwood, D. A.. 95Greenwood, J. A., 69Greezuitay, L. A., 139Gross, P.. 111, 123, 135Grote, lVi. J., 139Gruber, C. W., 17Gucker, F. Tu 19Guderian, R., 92
Haddow, A., 139Hagstrom, R. M., 159, 161, 172-173Haines, G. F., Jr., 20Hamilton, R. J., 17Hammond, C., 130Hammond, E. C., 141Hand, I. F., 40 :
Handyside, A. J., 166, 168, 174-175Harris, J., 69Harris, W. B., 17Harrison, L E., 95Hatch, T. F., 8, 111, 119, 120, 123Haythorn, S. R., 131Helwig, H. L, 26Hemeon, W. C. L., 17, 20Hendrix, W. G.. 23Hess, V. F., 40Hewson, E. W., 17Hilding, A. C., 122Hill, A. C., 93, 94Hill, I. D., 148, 168, 175Hitchcock, A. E., 93, 94Hodkinson, 3. R., 63Hoffman, P., 19Holbrow, G. L., 71Holden, F. R., 95Holland, W. W.,162;163, 166, 167,
172 - 173,174 -175 .
Holma, B., 122Holzworth, G. C., 51Horning, E. S., 189Horton, R. J. M., 164Horvath, H., 19, 54, 56, 57,59Hudson, J. D., 66, 67Hueper, W. C., 187Huey, N., 81Humphreys, W. 3., 43Hurd, F. K., 23
Ide, H. M., 20'Imada, M., 57
Jacobs, M. B., 65, 69, 153, 154, 171Jacobson, J. S., 93, 94Jennings, 0. E., 94Jens, W., 24, 25Johnstone, H. F., 136Jones, E. E., 26Joosting, P. E., 151, 153, 158Joslii, S., 140Junge, C. E., 11, 23, 53, 54Jurksch, G., 17Jutze, G. A., 17
Kaiser, E. R., 25, 107Kakis: F., 105Kallai, T., 58, 59Kanitz, S., 162, 172-173Katz. M., 17, 22Keagy, D. M., 21Keenan, R. G., 137Kemeny, E., 21Kemnitz, D. A., 5Kenrick, G. W., 39Kerka, W. F., 107Klarman, H. E., 84Kline, D. B., 41Knowelden, J., 166, 168, 174-175Kolb, L. H., 139Kolesnichenko, T. S., 139Korff, F., 39Kotin. P., 120. 132, 136, 137, 138,
141Krahl, V.E., 111Kramer, G. D., 21, 22Kreichelt, T. E., 5Kuepel, R. E., 138Kurland, L. T., 156Kuschner, M.. 140
La Belle, C. W., 135, 136Lainhart, W. S., 137La Mer, V. W., 118Landahl, H. D., 114, 118Landau, E., 159, 162, 164, 172-174Landsberg, H., 38, 39, 40, 41Langer, G., 71Larrabee, C. P., 66, 67, 68, 69Lawther, P. J., 153, 168, 169, 171,
175Le Clem, E., 69, 81Lee, G., 113Lee, R. E., Jr., 19, 26Lehmann, C., 118Lehmann, K., 117Lemke, E. E., 12Leonard, A. G., 154, 155Linnell, R. H., 105Lippmann, M., 17, 122Lloyd, T. C., 167Lodge, J. P., 19, 20, 23
Long, J. E., 135, 136Ludwig, F. L., 19Ludwig, J. H., 42, 43Lunn, J. E., 166Lynch, J. R., 137
Mac Phee, R. D., 26Magill, P. L., 95Mantel, N., 140Manzhenko, E. G., 167, 174,-175Marcus, S. C., 167Mark, H. L., .106Markul, I., 138Markush, R. E., 157Martin, A. E., 152, 153, 156, 171-
172Mateer, C. L, 40McCaldin, R. 0., 167McCarroll, J., 150, 154, 156, 171-
172McConnell, W. J., 117McCormick, R. A., 19, 37, 38, 42,
43McCrone, W. C., 18McCune, D. C., 93, 94McDermott, M., 133McKee, H. C., 105McMullen, T. B., 16McNerney, J., 119Meeker, G. 0., 11Meetham, A. R., 40, 41Megaw, W. J., 23Meller, H. B., 69, 71Metnieks, A. L., 23Michelson, I., 81Middleton, W. E. K., 51, 52Mie, G., 10, 55Miller, A., 135Miller, E. C., 137Miller, P. M., 94Miller, W. S., 111Milley, P. S., 123Miner, M. L., 95Mitchell, J. M., Jr., 43Mitchell, R. I., 111Moll, A. J., 136Morrow, J., 105Morrow, P. E., 111, 118, 119, 121Mountain, I. M., 150, 156, 171-172Mountain, J. D., 149, 156, 171-172Mueller, P. K., 26, 57
Nadel, .1. A., 17, 132Nader, J. S., 19Nagelsehrnidt, G., 69Nan, C. A., 132Neal, J., 132Nelson, N., 113, 117, 118, 122Neuberger, H., 40Ney, F. G., 118Noll, K. E., 55, 57Nussbaum, R., 92
Nthi 1 '1. .41.4
O'Connor, J. J., Jr., 81O'Konski, C. T., 19Orr, C., 23Ortiz, H., 39'Ott, R. R., 105Owens, J. S., 117Ozolins, G., 12
Paocagnella, B., 167, 174-175Pack, M. R., 93, 94Pajenkamp, H., 92, 93Palm, P. E., 119Palmes. E. D., 113, 117Parish, S. B., 89Park, J. C., 21Parker, A., 71Pascua, M., 137Pate, J. B., 19Patterson, H. S., 117Patterson, R. K., 19, 26Pattie, R. E., 130, 131, 136Paulus, H. J., 154Pavanello, R., 167, 174-175Payne, W. W., 138Peirce, G. J., 89, 91Pemberton, J., 157, 158, 159, 164,
172-174Pesarin, F., 167, 174-175Peterson, C. M., 54Peterson, J. T., 43Petrie, T. C., 72Petrilli, F. L., 162, 172-173Pfitzer, E. A., 123Phillips, P. H., 95Pickard, H. B., 19Pilat, M. J., 54, 56Pitts, J. N., Jr., 19Plotkin, T., 113Policard, A., 123Pollack, L. W., 23Potter, J. G., 41Pregermain, S., 123Preining, 0.,11, 58, 59Preston, R., St. J., 66, 69Prindle, R. A., 164, 167,173 -174Przeznecic, E., 93Pueachel, R. F., 10, 19, 64, 55, r6,
59Pnrvance, W. T., 23Pybus, F. C., 137Pylev, L. N., 139
Quebedeaux, W. A., 105
Raymond, V., 92Reed, 3. I., 153, 164, 171Rees, W. H., 71 ,72Rehm, F. R., 24, 25Reid, D. D., 162, 163, 165, 167, 172-\ 178, 174-175Reid, L., 185Rich, S., 94
or,
206
Rich, T. A., 23Ridker, R. G., 84Rinehart, W. E., 135Robbins, R. C., 10Robison, C. B., 101Robinson, E., 19, 51, 52, 53, 58Robinson, N., 38Robson, C. D., 17Roderick, W. R., 105Roesler, J. R., 19Ronald, G., 18Rose, A. H., 24Rossano, A. T., 105Bowling, H., 26
SaMotti, U., 139Saito, Y., 117Salem, H., 130, 132, 136Samuels, S. W., 99, 101Sanderson, H. P., 15, 22Sanyal, B., 66, 69Sauberer, F., 39Sawicki, E., 138, 140Sawyers, L. A., 113Sayers, R. R., 117Scheffer, F., 93Schilling, F. J., 165, 173-174Schnurer, L., 131Schonbeck, H., 92Schrader, J. H., 39Schrenk, H. H., 134Schueneman, J. J., 101Schusky, J., 99Scott, J. A., 152, 171Scott, W. E., 106Selikoff, L J., 130Seltser, R., 162, 163, 167, 172-173,
174-175Sensenbaugh, J. D., 17Seriff, N. S., 153, 171Shabad, L. M., 139Shaddick, C. W., 151, 171Shaffer, N. R., 12Shaver, J., 135Sheesley, D., 11Shelden, J. M., 17Sheleikhovskii, G. V., 37, 88, 39Sheppard, P. A., 37Shubik, P., 189Shupe, J. L, 95Sievers, F. J., 94Silverman, L., 23, 113Sisson, L. B., 69, 71Skidmore, J. W., 69Slatgr, R. W., 17Smith, B. M., 7:0Smith, R., 16Smith, W. S., 27, 101Speizer, F. E., 168, 175Spiegelman, J., 122Sprague, H. A., 159, 161, 172-178Spunky, K., 20
-213
Stagg, J. M., 39, 40Stalker, W. W., 20, 22, 101Stanley, T., 138Steiner, P. E., 138Steinhauser, F., 39Steinhubel, G., 91Shembridge, V., 132Stern. A. C., 19, 51, 52, 53, 58, 72Stevenson, H. J. R., 19Stewart, M. J., 139Stocks, P., 157, 171-172Stoeber, W., 17Stokinger, H. E., 129, 130, 134Stone, R. W.. 162, 163, 167, 172-
173, 174-175Stout, A. P., 141Stout, G. E., 42Stratmann, H., 93Strauss, W., 23Strethlow, C., 122Sullivan, J. L., 22Sutton, 0. G., 106Swartztrauber, P., 19
Tabershaw, I. R., 137Tabor, E. C., 71, 72, 139, 140Taylor, J. R., 26Tebbens, B. D., 72Telford, J. W., 42Thomas, B. G. H., 117Thomas, M. D., 93, 94Thompson, R. M., 117Tice. E. A., 65, 71Tinker, C. M., 168, 176Tomashefski, J. F., 112Tourangeau, F. J., 118Tourin, B., 81Toyama, T., 162, 167, 172-173, 174-
175Tracewell, T. N., 118Transtrum, L. C., 93, 94Tremer, H., 132, 136Tufts, a J., 23Turk, A., 105, 106
Uhlig, H. H., 80Underhill, D. W., 132, 136Upham, J. B., 68
Valko, P., 43Van Haut, H., 193Van W.ijk, A. M., 117Venezia-, R., 12Verma, M. P., 165, 173-174Vernon, W. H. J., 65Verssen, J. A., 12Vintinnnr, F. J., 182Volz, F., 19, 87, 48Von Zuilen, D., 150, 153, 158Vorwald, A. J., 134
I
Wagman, J., 10, 19, 26Wagner, W. D., 130Walkenhorat, W., 117, 119Waller, R. E., 71, 165, 169, 173 -174Walter, E. W., 150, 156, 171-172Walther, J. E., 106Walton, W. H., 17Wang, C. S., 54, 58Warren, W. V., 71, 72Watanabe, H., 154, 167, 171, 174-
175Wedd, C. D., 131Weibel, E. W., 114
Weinstein, L. H., 93, 94Weisbrod, B. A., 84Went, F. W., 53Wentzel, K. F., 92West, P. W., 19Whitby, K. T., 23Wicken, A. J., 162Williams, J. D., 99Williamson, J. B. P., 69Wilms, W., 93Wilson, I. B., 118Winkelstein, W., 158, 172-173Wiseley, D. V., 137
::214.
Wohlers, H. C., 106Wolfson, P., 122Wright, G. W., 167Wynder, E. L., 19
Yancey, A. R., 113Yant, W. P., 117Yarmus, L., 113, 117, 118Yocom, J. E., 69, 71
Zeidberg, L. D., 101, 156, 159, 161,164, 172-173, 173-174
Zickmantel, R., 64, 173-174Zwi, S., 132
. 207
A
Acrolein toxicity, 135, 186Adhesion properties, 8-9Adhesive dustfall collectors, 17Adsorbed substances
discussion of, 130Adsorption
role in odors, 107role in toxicity, 130
Aerodynamic factorsrespiratory tract, 113-114, 115-
116Aerosols
pulmonary effects, 131-137reduction of toxicity, 130-131toxicity, 129
Agerelationship to mortality, 148,
151, 158, 160Air pollution episodes, 15, 150-154Alveolar deposition, 119Ammonia toxicity, 122,135Animal odors, 107Aromatic hydrocarbons as carcino-
gens, 137-141Asbestos
toxicity of, 129-130, 150Automobile exhaust emissions, 26Automobiles
corrosion of, 71
B
Berylliumtoxicity of, 129-130, 150
Birmingham, Alabamapublic opinion survey, 101
Bronchitismorbidity studies of, 156, 161-
169mortality studies of, 150-154,
156-161Brownian motion, 9, 113Buffalo, New York
mortality studies, 158, 160, 161,170, 171
public opinion survey, 101Building materials
deterioration of, 69Buildings
deterioration, 78-74
208
SUBJECT INDEX
C
Canadamorbidity studies, 163, 164, 173
Cancerlung, 137, 141, 157-162mortality, 157, 160-162stomach, 158, 161-162
Carbon blacktoxicity of, 132
Carbon particlestoxicity, 135
Carcinogenic hydrocarbons, 137-142
Carcinogensdiscussion of, 137-142
Cascade impactors,. 17, 19Cement plants
emissions from, 24, 25-26Cement-kiln dust, 89-93Channel black effects 'resp. tract,
132Chemicals
odors from, 107Chicago mortality studies, 150Children
morbidity studies, 165-167Chlorides
corrosive effects, 71Clearance model
respiratory system, 120-121Clearance of particulate matter in
the respiratory system, 121-123Climate
effects of particulate on, 35, 42-44
Climatic changeworld-wide, 42-44
Coal combustioneffects of smoke on animals, 131-
132emission from, 24, 27
Coal combustion gasescorrosive effects, 69-70
Coal dustdeposition, 117physiological effects of, 133
Combustible waste odors, 107Combustion odors, 107Combustion products
corrosive effects, 69-70Computer techniques of sampling,
19
Copper alloyscorrosion of, 6869
Corn oil particlesdeposition, 118
Corrosion of metals, 65-69, 72-74Costs of air pollution damage, 79-
84Cotton
soiling and deterioration of, 72,74
Crust formation on plants, 89-93Cyclonic collectors, 17
DDeposition
respiratory system, 112-119Deposition (dust) on vegetation,
89-96Desorption
odorants, 106-108Deterioration of materials, 65-74Detroit
mortality studies, 150, 154, 171Diurnal variation
particulate, 40, 41Dublin, Ireland
mortality study, 154, 155Dust
corrosive effects, 65-74effects on resp. tract, 112-119effect on textiles, 71-72, 74
Dust components, 92-93Dust mineral
deposition, 117Dustfall
description of, 11, 16-17seasonal variation, 39typical urban values, 17
Dustfall collectors, 17-19Dustfall jars, 17
Economic effects, 79-85Economical level
relationship to mortality, 156-158, 159-162, 163, 164, 167,170, 176
Electrical instrumentscorrosion of, 69
Electron microscopy, 20, 23Elutriators, 17Emission factors, 24Emission inventories, 12
Englandmorbidity studies, 154-156, 161,
162, 163, 164-169, 171-176mortality studies, 150-153, 154,
156-159, 171-176Epidemiological studies, 150-154Exacerbation of chronic diseases,
148-149, 154-156, 161-176Extinction
dependence on particle size, 55
F
Ferric sulfatetoxicity, 132 -133
Filterssampling, 20-22
Fluorideseffects on vegetation, 93-94
Fluorosisanimal, 95
Fogcorrelation with mortality, 150-
163Food odors, 107Formaldehyde
toxicity, 122, 135, 136Foundry
odors from, 107Foundry dust
effects on vegetation, 94France
economic effects of air pollutionin, 81
Fuel oil combustionemissions from, 24
G
Gas and particulate mixturessynergistic pulmonary effects,
134-137Gases
toxicity of, 134-137Great Britain
economic effects of air pollutionin, 81
medical effects of air pollution,150-159, 161-169, 171-176
H
Hazeparticulate size distribution of;
52-53High-volume sampler, 22-23Hydration process
dust crust, 91-92Hydrocarbons as carcinogens, 138-
141Hygroscopic particles
effect on pulmonary irritants,
IIllumination
seasonal variation, 37Industrial odors, 107International Standard Calibration
Curve for refiectometers, 21Irkutsk (U.S.S.R.)
morbidity studies, 167, 174Iron
corrosion of, 65-69Iron dust
effect on textiles, 72Iron oxide
effects on vegetation, 94Italy
morbidity studies, 162, 167, 173,174
JJapan
morbidity study, 162, 167, 173,174-175
mortality study, 154, 171
LLeaves
dust effects on, 89-96Light absorption, 52-53Light scattering, 9-10, 37-38, 52-
63, 54-58Linen
soiling and deterioration of, 71-74
Londonmorbidity studies, 154-156, 162,
163, 165-167, 168-169, 172, 173,174, 175
mortality studies, 56-158, 171-172
Lung deposition, 118-119Lung dynamics
model of, 114-116
M
Magnesium oxideeffects on vegetation, 94
Membrane filters, 20Messthelioma, 129-130Metals (see specific metal)Meuse Valley
mortality studies, 150Mie solutions, 54-55Morbidity
correlation with pollution, 148-149, 154-156, 161-176in children, 165-167incapacity for work; 164-165
Mortalitycorrelation with acute air pollu-
tion episodes, 148, 150-154exposures to air pollution, 148,
136 150-154, 156-161, 169-176
Long term, 156-161Motor vehicles
emissions from, 26Municipal incineration
emissions from, 24-25
N
Nasal fractionation, 118Nashville, Tennessee
morbidity studies, 164, 173mortality studies, 160, 161, 173public opinion survey, 100-101
Nephelometer, 19NewHampshire (Berlin)
Morbidity study, 164, 173New York City
morbidity studies, 154-156, 165,170, 171, 173, 176
mortality studies, 156, 170-171Nickel
corrosion of, 67-69Nitrogen dioxide
toxicity, 135Nucleation properties, 8-9Nuisance surveys, 99-102
Odorsassociation with particles, 106-
107emission sources, 107
Open hearth furnacesemissions from, 24
Optical density, 20-22Optical properties, 9-10Osaka
mortality study, 154, 171
Paint odors, 107Painted surfaces
deterioration of, 71, 72-74Particle formation mechanisms, 10-
11Particle-gas reactions, 10Particle size
role in measuring techniques, 149role in pulmonary deposition,
114, 118-119role in pulmonary effects, 182 -
133distribution, 58, 117
Pennsylvania communitiesmorbidity study, 167-168, 175
Philadelphia, Pennsylvaniaeconomic effects of air pollution
in, 83
209
Photochemical reaction model, 10Photometry, 20Photomicrographic atlas, 19Physiological response, 132-134Pittsburgh, Pennsylvania
economic survey of pollutiondamage, 180
Plantsdust effects on, 89-93
Pneumocoiosis, 122, 131Pneumonia
mortality, 157Poly-nuclear aromatic hydrocarbons
carcinogenicity of, 137Post office employees
morbidity studies, 163Precipitation
influence of particulates on, 40-42
Public opinion surveys, 99-102Pulmonary flow resistance, 132-
1,Pulmonary function
alterations in, 132-134
RRace
relationship to mortality, 156Rainfall (See Precipitation)Refinery
odors from, 107Reflectance, 21Reflectometer, 21Respiratory illness
relation to smoke level, 148, 162-167
Respiratory systemmodels of, 114-116
Respiratory tractanatomy of, 111-112
Retentionhuman vs. animal respiratory
system, 119respiratory system, 112-119
Rotterdammorbidity study, 168, 175
Rusting, 65-69, 72-74
S
Salford, Englandmorbidity studies, 164mortality studies, 158-159
Sampling methods; 17-23Scattering coefficient, '55-58Settling velocities, 16Sewage
odOrs from, 107Sex
relationship to mortality, 156Sheffield, England.'.
morbidity studies, 167, 168; 170,174
Smokecorrosive effects, 72-74toxicity of, 160-164
Smoke plumesoptical properties of, 53
Smoke shadecorrelation with mortality, 154
Smokingcigarette, 137, 141, 149-160, 168,
161, 162, 163, 166Sodium chloride
corrosive effects, 71Solar radiation
effects of particulates on, 35-38physical factors effecting, 38-39seasonal variations, 39-40weekly variations, 39
Soot,corrosive effects, 65-74effects on textiles, 71-74effects on vegetation, 89-94
Sorption properties, 8St. Louis, Missouri
economic effects of pollution in,83
public opinion survey, 99-100Steel
corrosion of, 65-69, 72-74Stokes law, 5-6Sulfur dioxide
corrosive effects, 65odor, 107toxicity of, 130-131, 132, 136-137
Sulfuric acideffects on vegetation, 94
Sulfuric acid manufacturingemissions from, 24
Supersaturationnuclei, 23
Surface coatingsdeterioration of, 69-71, 72-74
Surface properties, 8-9Surveys of damage, 79-84Suspended particulate /.
means for urban areas, 11, 13-16Synergistic effects
gases and particulate, 135Synthetic textiles
soiling and deterioration of; 71-74
Syracuse, New Yorkeconomic effects of air pollution
in, 83
210
Tape samplers, 20-22Telephone workmen
morbidity studies, 162, 163irettshydro naphthalene
toxicity, 131
'217
Textilessoiling and deterioration of, 71-
74Toxicity
adsorbed substances, 130intrinsic of particulates, 129-130reduction of, 130-131
Transmissivityvariation with climate, 36
Transmittance, 20-21Trees
(lust effects on, 90-92Triphenyl phosphate
deposition, 117Turbidimetry, 19Turbidity, 37
U
Upper Ohio River Valleyeconomic survey of pollution
damage, 81, 82
V
Varnished surfacesdeterioration of, 69-71, 72-74
Vegetablesdust effects'on, 89-96
Visibility, 51-61effect of fog upon, 53-54effects of natural aerosols on, 63effects of particulates on, 36-38,
53-53Volatile particles, 106
W
Washington, D.C. (Suburban)economic effects of air pollution,
83Waste decomposition
odors from, 107
Woolsoiling and deterioration of, 71-
74
X
X -ray diffraction, 19
Zinccorrosion of, 66, 67-68; 72-74
Zinc dusteffect on textiles, 72
Zinc saltscorrosive effects, 71
ACKNOWLEDGEMENTS
The following sources, in most instancesthe copyright holders, have granted permis-sion to the National Air Pollution ControlAdministration to include the following fig-ures and tables in the Air Quality Criteria:
Table 1-1.Los Angeles data courtesy of LosAngeles County Air Pollution Control Dis-trict
Table p. 26. Chemical. Processing Engineer-ing, London
Table p. 27.American Society of Mechani-cal Engineers, New York, N. Y.
Table 2-2.The Gray Printing Company,DuBois, Pennsylvania
Tables 3-1, 8-1.Air Pollution Control As-sociation, Pittsburgh, Pa.
Table 3-2.Reinhold Book Corporation, NewYork, N. Y.
Table 4-1.Iron and Steel Institute, London
Tables 4-2, 4-3.American Society for Test-ing & Materials, Philadelphia, Pa.
Table 5-1.Mellon Institute, Pittsburgh, Pa.
Table 10-2.American Industrial HygieneAssociation, Detroit, Mich.
Tables 10-3, 10-4, 11-2, 11-3, 11-4.Ameri-can Medical Association, Chicago, Ill.
Table 10-5.American Association for theAdvancement of Science, Washington, D.C.
Table 10-6.National Tuberculosis & Res-piratory Disease Association, New York,N.Y.
Table 11-1.Pergamon Press, Inc., NewYork, N. Y.
* U. 8. GOVERNMENT PRINTING OFFICE : 1969-347411/32
Figure 1-1.Academic Press, Inc., NewYork, N. Y.
Figures 1-3, 2-2, 3-1, 3-4, 3-5, 3-6, 9-4, 9-5,9-6, 9-7.Pergamon Press Inc., NewYork, N. Y.
Figure 1-4.American Industrial HygieneAssociation, Detroit, Mich.
Figures 2-1, 3-7, 7-2.Air Pollution ControlAssociation, Pittsburgh, Pa.
Figures 2-3, 2-4, 11-2.Controller, Her Maj-esty's Stationary Office, London, England
Figures 2-5, 3-1, 3-3.American Meteoro-logical Society, Boston, Mass.
Figure 3-8.American Chemical Society,Washington, D. C.
Figure 4-1.Iron and Steel Institute, Lon-don, England
Figure 4-2.American Society for Testing& Materials, Philadelphia, Pa.
Figure 4-3.District of Columbia HealthDepartment, Washington, D. C.
Figure 5-1.Environmental Health & SafetyResearch Associates, New Roc , NewYork
Figures 6-1, 6-2, 6-3.Ellis F. Darley, Uni-versity of California, Riverside, Calif.
Figure. 11-1.Royal Society of Health, Loridon, England
Figure 11-3.Royal Dublin Society, Dublin,Ireland
Figure 11-7.American Medical Associa-tion, Chicago, Ill.
Figure 11-8.British Medical Journal, Lon-don, England
211
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