What Is the Current State
of Air Pollution?
Roy L. Smith, Ph.D.US Environmental Protection
Agency Office of Air Quality Planning and
StandardsResearch Triangle Park, NC
Introduction• About me
• Topics covered by this presentation:− Fragmentation of air pollution programs and its
influence on how much we know (or don’t know)− Criteria air pollutants (“principal pollutants”)
• Sources of data• Trends• Projections
− Hazardous air pollutants (HAPs, or “air toxics”)• As above, but contrasted
− The aging of America• Demographic shifts• Migration• Mobility• As related to health risks associated with air
pollution
Subdividing Air Pollution: The Clean Air ActCriteria
pollutantsHAPs
6 Substances 188 Substances and categories
> 1000 Monitors 22 Monitors
Annual emission inventories since 1970
Triennial emission inventories since 1993
Subject to NAAQS Subject to industry-specific MACT standards
Ambient levels and exposures well-described
Ambient levels and exposures mostly poorly- or not-described
Dose-response intensely studied
Dose-response information varies from good to nonexistent
What We Know: Criteria Pollutants
www.epa.gov/airtrends
EPA Criteria Pollutant Monitoring Network
Pollutant
Locations
Frequency
O3 1167 Hourly (May-Sep)
PM2.5 1200 24-h avg.,Mixture of every 1, 3, or 6 days
PM10 1214
SO2 592 Hourly
NO2 437 Hourly
CO 498 Hourly
Pb 247 24-h avg. every 6th day
Clear Skies: Fine Particulate Projections
Clear Skies: O3 Projections
Clear Skies: Risk Projections• Reductions in fine particles and ozone1
under Clear Skies would improve public health. By 2020, Americans would annually experience approximately:
• 14,100 fewer premature deaths; (An alternative estimate projects 8,400 fewer premature deaths)
• 8,800 fewer cases of chronic bronchitis;
• 23,000 fewer non-fatal heart attacks;
• 30,000 fewer hospitalizations/emergency room visits for cardiovascular and respiratory symptoms;
− Included in this total are 15,000 fewer hospital and emergency room visits for asthma.
− Included in this total are hundreds of thousands fewer respiratory symptoms and illnesses for asthmatics, including approximately 180,000 fewer asthma attacks.
• 12.5 million fewer days with respiratory illnesses and symptoms, including work loss days, restricted activity days, and school absences.
What We Know: Hazardous Air Pollutants
HAP Contributions to Tox-Weighted Emissions for Cancer
1990 1996
2010 2020
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
0
1
2
3
4
5
6
7
8
M A & O F ON NON
Other HAPs
POM
Perchloroethylene
Naphthalene
Coke Oven Emissions
Chromium VI
Benzene
Arsenic
1,3-Butadiene
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
0
1
2
3
4
5
6
7
8
M A & O F ON NON
Other HAPs
POM
Perchloroethylene
Naphthalene
Coke Oven Emissions
Chromium VI
Benzene
Arsenic
1,3-Butadiene
0
0.5
1
1.5
2
2.5
3
M A & O F ON NON
1990
2010 2020
1999
Without CAA
HAP Contributions to Tox-Weighted Emissions for Noncancer Effects
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
M A & O F ON NON
Billion
s
Other HAPs
Hydrochloric Acid
HexamethyleneDiisocyanate
Chlorine
Acrolein
1990
2010 2020
1999
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
M A & O F ON NON0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
M A & O F ON NON
Billion
s
Other HAPs
Hydrochloric Acid
HexamethyleneDiisocyanate
Chlorine
Acrolein
1990
2010 2020
1999
1.3 ug/m3 = 1e-5 risk
Comparisonwith
Ambient Concentration
Monitoring
Emission Inventory
Development
Emission Processing
(EMS-HAP)
Air
Dispersion
Modeling
(ASPEN)
Inhalation
Exposure
Modeling
(HAPEM)
Risk
Assessment/
Characterization
Dose- Response
Assessment
Components of the NATANational-Scale Assessment
Can zoom in to area of concern
NATA Model to Monitor Comparisons
1.0=Agreement
Model overprediction
Model underprediction
75th percentile
25th percentile
Median
Benzene found very good agreement
Metals appear to be
underpredicted by NATA
What We Know: Demographics of Aging, and How They Influence Exposure to Air Pollution
http://www.census.gov/prod/2002pubs/censr-4.pdf
http://www.census.gov/prod/2003pubs/censr-10.pdf
http://www.census.gov/prod/2003pubs/censr-10.pdf
http://www.census.gov/prod/2001pubs/c2kbr01-10.pdf
http://www.census.gov/prod/2002pubs/censr-4.pdf
http://www.census.gov/prod/2004pubs/p20-549.pdf
http://www.census.gov/prod/2004pubs/censr-19.pdf
Summary• State-of-the-art
−Air pollution programs fragmented by law and institutional history• Criteria pollutants separated from toxic
pollutants• Level of knowledge varies widely:
− Criteria > HAPs− Cancer > noncancer− Health > eco
• Analyses and projections tend to be specific to decisions rather than general to the entire program
Summary• Criteria Pollutants
−O3 and PM present most of the health risk
−Emissions and ambient levels:• Have improved substantially over the last 10-20
years…• …despite huge growth in population, GNP, and
energy use
−Information quality• Vast monitoring network, > 1000 stations for most
important• Annual emission inventories• Regular analyses of past AQ trends• Sporadic projection analyses that generally show
substantial further improvements are attainable
Summary• Hazardous Air Pollutants
−MACT program has decreased emissions…• ca. 3-fold by mass• ca. 2-fold by toxicity-adjusted mass• Made most gains in major and mobile sources• Emission projections show gains starting to erode
by 2010−NATA
• First analysis of entire air toxics universe• Identified most important HAPs nationally
(benzene, acrolein, POM, butadiene, Cr, naphthalene, chlorine, etc.)
• NATA too new to determine trends• NATA not yet used for projections
− First use due soon, however• Unlikely to overestimate actual exposures
Summary• Interaction of air pollution with aging
population−More people >65 than ever before; trend
continuing−Exposure to air pollution may differ because:
• Different behaviors− Relocation pattern & representation in population
• Tendency to live in areas of moderate air pollution− Less likely to relocate
• Longer exposure durations− Less likely to leave the house
• Exposure moderated less by daily activity patterns
• Different gender makeup• Potentially more susceptible to health effects