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ava i l ab l e a t www.sc i enced i rec t . com

www.e l sev i e r. com/ loca te / sc i to tenv

Urban air quality in the Asian region

Philip K. Hopkea,⁎, David D. Cohenb, Bilkis A. Begumc, Swapan K. Biswasc, Bangfa Nid,Gauri Girish Pandite, Muhayatun Santosof, Yong-Sam Chungg, Perry Davyh,Andreas Markwitzh, Shahida Waheedi, Naila Siddiquei, Flora L. Santosj,Preciosa Corazon B. Pabroaj, Manikkuwadura Consy Shirani Seneviratnek,Wanna Wimolwattanapunl, Supamatthree Bunprapobl,Thu Bac Vuongm, Pham Duy Hienn, Andrzej Markowiczo

aCenter for Air Resources Engineering and Science, Department of Chemical and Biomolecular Engineering, Clarkson University, Potsdam,NY 13699-5708, United StatesbAustralian Nuclear Science and Technology Organisation (ANSTO), Physics Division, Private Mail Bag 1, Menai 2234, NSW, AustraliacBangladesh Atomic Energy Commission (BAEC), Atomic Energy Centre, Dhaka (AECD), P.O. Box 164, Dhaka, BangladeshdChina Institute of Atomic Energy (CIAE), China National Nuclear Corp. (CNNC), P.O. Box 275-50, Beijing 102413, ChinaeBhabha Atomic Research Centre, Trombay, Mumbai 400085, IndiafCenter for Nuclear Technology of Material and Radiometry, National Nuclear Energy Agency (BATAN), Jl. Tamansari 71,Bandung 40132, IndonesiagHanaro Center, Korea Atomic Energy Research Institute (KAERI), 150 Dukjin-dong, Yusung-ku, P.O. Box 105, Daejon 305-600,Republic of Koreah Institute of Geological and Nuclear Sciences (GNS), 30 Gracefield Road, P.O. Box 31-312, Lower Hutt, New ZealandiDivision of Nuclear Chemistry, PINSTECH, Pakistan Atomic Energy Commission (PAEC), P.O. Box 1482, Nilore, Islamabad, PakistanjPhilippine Nuclear Research Institute (PNRI), Commonwealth Avenue, Diliman, P.O. Box 213, Quezon City 1101, PhilippineskAtomic Energy Authority, 60/460, Baseline Road, Orugodawatta, Wellampitiya, Sri LankalThailand Institute of Nuclear Technology (TINT), 16 Vibhavadi Rangsit Road, Bangkok 10900, ThailandmCentre for Radiation Protection, Institute of Nuclear Sciences and Technology, P.O. Box 5T-160, Cau Giay, VietnamnVietnam Atomic Energy Commission, 59 Ly Thuong Kiet, Hanoi, Vietnamo International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Agency's Laboratories (Seibersdorf and Headquarters),Physics, Chemistry and Instrumentation (PCI) Laboratory, Instrumentation Unit, SEIB, Wagramerstrasse 5, Postfach 100, 1400 Wien, Austria

A R T I C L E I N F O

⁎ Corresponding author. Tel.: +1 315 268 3861E-mail address: hopkepk@clarkson.edu (P.K

0048-9697/$ – see front matter © 2008 Elsevidoi:10.1016/j.scitotenv.2008.05.039

A B S T R A C T

Article history:Received 2 August 2007Received in revised form 12May 2008Accepted 21 May 2008Available online 29 July 2008

Over the past decade, member states of the Regional Co-operation Agreement (RCA), anintergovernmental agreement for the East Asia and Pacific region under the auspices of theIAEA with the assistance of international organizations and financial institutions such as theWorld Bank and the Asian Development Bank, have started to set in place policies andlegislation for air pollution abatement. To support planning and evaluate the effectiveness ofcontrol programs, data are needed that characterizes urban air quality. The focus of thismeasurement program describe in this report is on size segregated particulate air pollution.Such airborne particulate matter can have a significant impact on human health and urbanvisibility. These data provide the input to receptor models that may permit the mitigation ofthese impacts by identification and quantitative apportionment of the particle sources. Theaim of this report is to provide an overview of the measurements of concentrations andcomposition of particulate air pollution in two size fractions across the participating countries.

Keywords:PM2.5

PM10

PM10–2.5

AsiaMegacities

; fax: +1 315 268 4410.. Hopke).

er B.V. All rights reserved.

Fig. 1 –Map of the Asian region indicatingIndia, 5. Indonesia, 6. Korea, 7. Malaysia, 814. Thailand, and 15. Vietnam.

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Formany of the large cities in this region, themeasured particulatematter concentrations aregreater thanair quality standardsor guidelines thathavebeenadopted indeveloped countries.

© 2008 Elsevier B.V. All rights reserved.

1. Introduction

Increased economic development in the Asian region hasoften led to rapid and unplanned urbanization. Urban airpollution poses significant threats to human health and theenvironment throughout the developed and developingworld.The issue of urban air quality is receivingmore attention as anincreasing fraction of the world's population are now living inurban centers and are demanding a cleaner environment. Theenvironmental impacts are particularly severe in Asian regionwhere some countries have a combination of intense indus-trial activity, large populations, and increased motor vehicleusage. There has been growing recognition of the health effectproblems resulting from airborne particles in this region (HEI,2004). Although there is some routine monitoring data onparticulatematter concentrations. The focus has been on totalsuspended particle (TSP) or PM10 (particles with aerodynamicdiameters less than 10 μm) concentrations. Data on particlecompositions across this region are relatively scarce and limitthe ability to perform source apportionment or use them forother purposes such as health effects modeling.

KimOanh et al. (2006) presents summariesof PM2.5 andPM10

compositionsmeasured in Bandung, Indonesia, Bangkok, Thai-land, Beijing, China, Chennai, India, Manila, Philippines, andHanoi, Vietnambetween 2001 and 2004. In all six cities, the PM10

and PM2.5mass concentrationswere found to behigh, especiallyduring the dry season and frequently exceeded the correspond-ing 24 h US EPA standards at a number of the sites. The averagemass concentrations in the cities in the dry season ranged from

the locations of the pa. Mongolia, 9 Myanmar

44 to 168 and 54 to 262 μg/m3 while the concentrations rangedbetween 18 and 104 and 33 to 180 μg/m3 in the wet season forPM2.5 and PM10, respectively.

Fang et al. (2005) havereviewedtheavailabledata formetallicelementsmeasured acrossAsia during the period of 2000 to 2004.This review paper summarizes data from a number of episodicstudies that measure particulatematter. However, themeasure-ments are made with multiple collection devices for particles indifferent size ranges and analyzed by a variety of analyticalmethods. Much of the available data are for TSP at a time whenthe focus of current studies on health effects and otherenvironmental effects research are focused on PM10 and PM2.5.

Beginning in 1996, the International Atomic Energy Agencythrough its Regional Cooperation Agreement states in theAsian regions initiated an air pollution project to assist theMember States in collecting and analyzing particulate mattersamples (Smodis, 2007). The fifteen participating countrieshave developed the capability to sample, analyze, and utilizethe resulting data to assess particulate air pollution in anumber of locations across the region.

Chung et al. (2005) identified air pollution sources based onabout 500 airborne particulate matter (PM2.5 and PM10–2.5)samples collected in an urban region in the middle of Koreafrom 2000 to 2003. The concentrations of 25 elements in thesamples were measured by instrumental neutron activationanalysis (INAA). Positive matrix factorization (PMF) identified6 to 10 PMF factors, such as metal-alloy, oil combustion,diesel exhaust, coal combustion, gasoline exhaust, incinera-tor, Cu-smelter, biomass burning, sea-salt, and soil dust.

rticipating countries. 1. Australia, 2. Bangladesh, 3. China, 4., 10. New Zealand, 11. Pakistan, 12. Philippines, 13. Sri Lanka,

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Airborne particulate matter (APM) samples collected at asemi-residential area in Dhaka, Bangladesh, during the periodsof 1994 and 1997–2000 have been studied to assess the impact ofthe use of unleaded gasoline in Bangladesh (Biswas et al., 2003).No significant changes in the annual averages of APMmass andblack carbonconcentrationswereobservedover thisperiod.Theyearly average Pb concentration reached a maximum value of370 ng/m3 in PM2.5 in 1998. In 2000, the concentration decreasedto approximately one-third (106ng/m3) of theearlier valuesafterthe introduction of unleaded gasoline in 1999. The character-istics of aerosol chemical composition of few cities in Bangla-desh have been studied in sort term monitoring campaigns in2001 (Salam et al., 2003a,b). Begum et al. (2004) reported on thecomposition of samples of fine and coarse fractions of airborneparticulate matter (PM) collected in a semi-residential area ofDhaka, Bangladesh from June 2001 to June 2002 and in an urbanareaofRajshahi, a city innorthwesternBangladesh fromAugust2001 to May 2002. PM2.5 mass concentrations in Dhaka aver-aged 22.25 μg/m3 and in Rajshahi, PM2.5 averaged 22.47 µg/m3.PM10– 2.5 concentrations averaged 42.88 and 41.13 µg/m3 inDhakaandRajshahi, respectively. Subsequentmeasurementsata high traffic-impact site in Dhaka (Begum et al., 2005) reportedvery high concentrations of both fractions.

Hien et al. (2002) reported the compositions of fine andcoarse particles collected in Hanoi over the year beginning inAugust 1998. The annual mean concentrations (±standarderrors) from August 1998 to July 1999 were (87.1±3.1) µg/m3 forPM10 and (36.1±1.3) µg/m3 for PM2.5. Hien et al. (2004) examineddata from 1999–2001 using receptor models and trajectoryanalysis to explore the relative contribution of local and longrange transported aerosol to the PM2.5 and PM10–2.5 concentra-tions. They thenexamined thedata from2001 to2002 to identifythe formation of secondary particles on the mineral dustparticles (Hien et al., 2005).

Santosoetal. (2008) reported on the composition and sourceapportionment of fine and coarse particle samples collected in

Table 1 – Information on the sampling sites from which data ar

Country Site ID Latitude Lon

Australia 33 (Liverpool) 33.93 S 1535 (Lucas Heights) 34.05 S 15

Bangladesh Atomic Energy Centre 23.73 N 9Farm Gate 23.76 N 9

China Beijing 39.92 N 11Suburb 39.74 N 11

India Trombay 19.04 N 7Vashi 19.07 N 7

Indonesia Bandung 6.55 S 10Lembang 6.19 S 10

Korea Daejeon (Daehwa) 36.35 N 12Daejeon (Deokjin) 36.42 N 12

New Zealand Masterton 40.95 N 17Seaview 41.24 S 17

Pakistan Nilore, Islamabad 33.66 N 7Philippines Ateneo de Manila 14.63 N 12Sri Lanka AEA 6.933 N 7

AQM 6.95 N 7Thailand Bangkok — Pathumwan 13.75 N 10

Bangkok — Chatuchak 13.75 N 10Pathumthani — Klongha 14.02 N 10

Vietnam Hanoi 21.02 N 10

Bandung and Lembang, Indonesia between 2002 and 2004. Themean values of PM2.5 concentrations at Bandung and Lembangwere 14.03±6.86 and 11.88±6.60 µg m−3, respectively. Themean values of PM10–2.5 concentrations at Bandung andLembang were 17.64±9.42 and 7.10±7.04 µg m−3, respectively.

The current project is providing data that focuses on bothurban and suburban particle concentrations and compositionsthat affect urban air quality and thus, can produce significantadverse health and visibility effects in the high populationcities being monitored. These data can be used to assess thelikely significant impact of particulate air pollution on humanhealth and the potential mitigation of these impacts byidentification and quantitative apportionment of the particu-late matter sources, both local and regional.

Thus, this project is addressing a significant problem,particulate air pollution that exists in these participatingcountries. In addition, monitoring of particulate air pollutionover an extended time interval permits the assessment of theeffectiveness of the control strategies and provides the basis foraccountability studies as has been seen for removing lead fromgasoline inBangladesh (Biswas et al., 2003) or removing the two-stroke, three-wheel taxis fromthestreets ofDhaka (Begumet al.,2006). These data could also serve as the basis for epidemiolo-gical studies if appropriate health effects data are also available.

Although some of the participating groups have presentedresults of their sampling, analysis and source apportionmentstudies as described above, there has not been a comprehensiveexamination of thewealth of data from thesemultiple countriesproviding information on fine and coarse particle mass andcompositions for 22 locations across Asia covering 4 years ofsampling and analysis. Thus, this work provides an overview ofparticulate air pollution in these participating countries. Fig. 1shows the locationsof the15countries in the IAEAprogramwith12 of these countries supplying data over this period. Becausedata from some countries were not available prior to 2002, thedistributions and trends could only be assessed during this time

e reported

gitude Start date End date Site description

0.91 E 1/1/00 – Urban0.98 E 1/1/00 – Rural0.40 E 1/1/00 – Residential0.39 E 9/4/00 6/30/06 Urban6.33 E 6/95 5/13/04 Urban6.03 E 12/11/98 5/13/04 Suburban2.92 E 1/1/99 – Urban2.97 E 1/1/02 – Urban7.36 E 1/4/00 – Urban7.23 E 1/4/00 – Suburban7.40 E 11/6/98 – Industrial7.37 E 11/6/98 – Suburban5.65 E 1/1/03 12/31/04 Suburban4.91 E 4/1/02 11/1/04 Industrial3.26 E 4/17/02 Suburban1.07 E 10/1/98 – Residential9.833 E 4/1/00 – Residential9.88 E 7/1/03 – Urban0.49 E 1/1/00 12/31/02 Residential0.49 E 1/1/03 – Residential0.52 E 1/1/03 – Suburban5.85 E 4/1/98 – Urban

Table 2 – Details of the data reported by the participatingcountries

Countries Site Size Number of samples peryear

2002 2003 2004 2005

Australia 33 (Liverpool) Fine 100 102 101 102Coarse 100 102 101 102

35 (Lucas Heights) Fine 100 102 102 102Coarse 100 102 102 102

Bangladesh Suburban (AtomicEnergy Centre)

Fine 102 96 82 13Coarse 102 96 82 13

Urban (Farm Gate) Fine 103 98 45 NACoarse 103 98 45 NA

China Urban Fine 28 30 21 NACoarse 26 30 22 NA

Suburban Fine NA 12 61 NACoarse NA 12 61 NA

India Trombay Fine 103 113 111 114Coarse 103 113 111 114

Vashni Fine 81 95 118 109Coarse 81 110 118 109

Indonesia Bandung Fine 42 93 84 84Coarse 42 93 84 84

Lembang Fine 40 93 80 84Coarse 40 93 80 84

Korea Daejeon (Daehwa) Fine 51 59 98 102Coarse 51 59 98 102

Daejeon (Deokjin) Fine 51 59 98 102Coarse 51 59 98 102

Malaysia Fine 58 57 52 25Coarse 56 57 52 25

NewZealand

Masterton Fine 44 45 73 NACoarse 44 45 80 NA

Seaview Fine 49 30 NA NACoarse 51 30 NA NA

Pakistan Nilore Fine 88 72 99 84Coarse 88 72 99 84

Philippines Ateneo de Manila Fine 77 83 80 95Coarse 80 85 81 95

Sri Lanka AEA Fine NA 57 30 42Coarse NA 53 29 20

AQM Fine 26 22 26 38Coarse 23 22 23 38

Thailand Urban (Bangkok) Fine 48 99 104 102Coarse 48 99 104 102

Suburban(Pathumthani —Klongha)

Fine NA 87 100 91Coarse NA 87 100 91

Vietnam Hanoi Fine 60 50 50 86Coarse 60 50 50 86

Fig. 2 –Box and whisker plots of the distributions of PM2.5

across the Asian region.

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interval. This report describes the distributions of mass andsome major species concentrations across the region. Moredetailed descriptions of the data on a country-by-country basisare provided in the supplemental material for this paper.

Fig. 3 –Box and whisker plots of the distributions of PM10–2.5

across the Asian region.

2. Experimental methods

Participating countries were provided with the Gent/IAEAstacked filter unit (SFU) particle sampler (Hopke et al., 1997)capable of collecting particulate matter in PM10–2.5 and PM2.5

size fractions. The samples were collected on an 8 µm pore

nuclepore filter for the coarse fraction sample and on a 0.4 µmpore nuclepore filter for the fine fraction sample. Generally,the samples were collected for a 24 h period at least once perweek at an urban residential and a suburban residential site.In some locations, it is not possible to collect the sample overthe entire 24 h because the high concentrations lead to filterclogging. Thus, the sampler was operated alternating time onand time off (e.g., 1 h on followed by 1 h off) over the course ofthe 24 h period to provide a representative sample during thatday. Information regarding the sampling sites and analyticalmethods employed are provided in Table 1.

The collected samples were analyzed using various nuclearanalytical methods including Particle-Induced X-Ray Emission(PIXE), X-ray Fluorescence (XRF), and Instrumental NeutronActivation (INAA). These methods are described in detail byLandsberger and Creatchman (1998). Light absorbing carbon

Fig. 4 –Box and whisker plots of the distributions of PM10

across the Asian region.

Table3 – Statisticalvaluesof fineparticlemassconcentrationsof the participating countries over the period of 2002 to 2005

Countries— site

Number Minimum Maximum Average SD

Australia 33 303 1.5 45.5 7.62 4.36Australia 35 304 0.8 27.9 5.35 3.82Bangladeshurban

246 2.3 293.5 48.19 40.65

Bangladeshsuburban

280 2.3 105.5 28.74 18.61

China urban 79 4.6 96.2 28.04 18.7Chinasuburban

73 7.1 179.5 42.14 31.46

India —Trombay

441 4.5 82.0 37.34 15.37

India — Vashi 403 7.7 115.8 44.69 17.68IndonesiaBandung

301 0.4 163.0 16.14 11.59

IndonesiaLembang

285 0.3 180.0 12.97 12.45

ROK — Daejeon(Daehwa)

206 0.6 62.4 10.45 7.73

ROK — Daejeon(Deokjin)

208 3.1 29.3 12.48 5.58

Malaysia 50 10.9 52.1 29.15 10.03NewZealand — M

162 0.0 42.3 9.38 9.26

NewZealand — S

79 4.9 18.5 3.68 3.3

Pakistan 258 0.0 88.4 14.43 9.82Philippines 240 2.8 51.4 27.2 8.42Sri Lanka —AEA

87 1.7 61.8 23.87 11.77

Sri Lanka —AQM

74 8.3 110.0 34.16 16.84

Thailand — 353 3.5 83.2 23.82 9.93

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(black carbon, BC) was measured using an EELS reflectometerthatmeasures the reduction in reflectedwhite light (Biswasetal.,2003; Begumet al., 2004).A fewcountriesused laser transmissionmeasurements of black carbon (Taha et al., 2007). This assess-ment focuses on the particlemass concentrations and composi-tion data from 2002–2005. For several countries, only mass andBC data were available because of difficulties with theiranalytical systems. Table 2 provides the details on the numberof samples collected in each size range during each of year of thestudy. Discussion of the composition data from the individualcountries is provided in thesupplementalmaterial for thispaper.

urbanThailand —suburban

278 1.6 49.9 20.21 8.8

Vietnam 160 11.0 90.0 35.84 15.52

3. Results and discussion

Air pollution has been increasing rapidly in developingcountries. Although there are ongoing projects to controlpollution in these countries, data provided by the participated

Fig. 5 –Box and whisker plots of the distributions of the ratioof PM2.5 to PM10 across the Asian Region.

countries indicate that in many areas, air quality falls belowthe standards. Figs. 2 and 3 show the distributions of fine andcoarse mass in the participating countries in the form of boxand a whisker plots. The median, 10th and 90th percentilelimits, outliers, median(solid line), andmean (dotted lines) areshown. The United States' National Ambient Air QualityStandard (NAAQS) for annual average PM2.5 is 15 µg/m3 whilethe 24 h standard is 35 µg/m3. Lines representing thesestandards are shown in Fig. 2.

Adding these two values together provide estimates ofPM10. The PM10 distributions are provided in Fig. 4. The U.S.NAAQS annual average PM10 standard value is 50 µg/m3 andthe 24-hour value is 150 µg/m3. It is clear from the Fig. 4 thatmost of the locations would be in violation of the US annualaverage standards. It can be seen that majority of the sitesshown in the Fig. 2 (top) would also violate the annual averagestandards for PM2.5 concentrations of 15 µg/m3. Hopke et al.(1997) showed that the GENT/IAEA sampler will underesti-mate PM2.5 because the 50% collection point is closer to 2.2 µmand not 2.5 µm. Thus, from the observed PM concentrations,there are concern that there is a strong potential for adverse

Table 4 – Statistical values of coarse particle massconcentrations of participating countries over the periodof 2002 to 2005

Countries— site

Number Minimum Maximum Average SD

Australia 33 303 0.7 68.1 10.49 7.47Australia 35 304 0.6 52.6 9.19 7.42Bangladeshurban

246 3.2 656.1 45.76 37.71

Bangladeshsuburban

280 3.2 335.3 48.49 40.55

China urban 78 5.7 196.1 58.3 29.24Chinasuburban

73 9.1 387.0 109.29 56.47

India —Trombay

441 8.0 260.9 37.34 15.37

India —Vashi

418 16.7 235.0 82.83 33.01

IndonesiaBandung

301 2.7 81.6 17.56 8.35

IndonesiaLembang

268 0.4 109.2 8.62 11.02

ROK—Daejeon(Daehwa)

207 3.1 103.5 24.7 15.33

ROK—Daejeon(Deokjin)

208 2.0 64.3 12.62 9.58

Malaysia 62 7.0 32.5 18.57 5.72NewZealand — M

169 2.1 25.0 7.42 4.23

NewZealand — S

78 1.1 19.0 6.95 2.23

Pakistan 258 0.0 348.8 67.45 49.95Philippines 309 0.0 157.3 22.78 14.11Sri Lanka AEA 82 9.0 219.9 58.82 32.71Sri Lanka AQM 68 4.6 251.4 73.37 38.02Thailandurban

353 6.0 149.6 38.67 21.87

Thailandsuburban

278 1.3 76.9 25.77 13.26

Vietnam 160 9.0 151.8 50.29 25.1

Fig. 6 –Box and whisker plots of the distributions of blackcarbon (BC) across the Asian region.

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public health effects and further, there are substantialproblems with the air quality in the region and need toidentify the sources of the particulate matter so that it wouldbe possible to plan for improvements in air quality by selectivecontrol of the major sources.

There are notable differences in the relative concentrationsof PM2.5 and PM10 across the region. Fig. 5 presents thedistributions of the ratios of PM2.5 to PM10 for each of thesampling locations. It can be seen that a wide range of valueswere observed. In general, the ratio is less that than 0.5indicating that there are higher coarse particlemasses atmostlocations. The urban site in China, the suburban site inLembang, Indonesia, the KAERI site in Korea, Masterton inNew Zealand, and the site in the Philippines havemean PM2.5/PM10 ratio values greater than 0.5. The Nilore site in Pakistanhas the smallest average value indicating the highest coarsefraction concentrations as can be seen in Fig. 3.

Statistical measures such as arithmetic average PM massconcentrations, standard deviations, maximum and mini-mum values for each participating countries are given inTables 3 and 4, respectively. From Tables 3 and 4, PM con-centrations across most of the participating countries would

exceed the latestWorld Health Organization guidelines (WHO,2005) and would violate the US NAAQS standards. HoweverChina, Pakistan, Bangladesh, India and Sri Lanka are a cause ofconcern. Increases in coal combustion, increased populations,and heavy traffic in urban centers might be a major factor forhigh pollution in India and China. Use of more motor vehiclesand dense population are a chief contributors for pollution inPakistan and Bangladesh. Even in countries with supposedlyclean air like Australia and New Zealand, motor vehicles andsmoke from domestic burning are key political as well asscientific issues.

In the subsequent tables, statistical summaries are pro-vided for the elements that were measured by the participat-ing countries. All of the species have not been reportedbecause, some of the participants were unable to report theconcentrations for certain elements because of their limita-tions in their analytical methodology. Also, species for whichmore than 50% of samples were below detection limits of theinstruments were neglected.

3.1. Variations in species concentrations across the region

Variation in elemental concentrations of fine and coarseparticulate matter over the 4 year period in the participatingcountries will be examined.

3.1.1. Black carbon (BC)The black carbon content of the fine fraction filters wasmeasured using a reflected light instrument provided by theIAEA to the participants (Biswas et al., 2003). Fig. 6 shows theBC concentrations in the participating countries. BC was notmeasured for the Chinese samples. These concentrations areoperationally defined based on the amount of reflected lightthat is absorbed by the filter sample and an assumed massabsorption coefficient. Most countries used a mass absorptioncoefficient of between 5 and 10 m2/g to convert reflectancemeasurements to µg/m3. It is related to the concentration of

Fig. 7 –Box and whisker plots of the distributions of fine (top)and coarse (bottom) lead across the Asian region.

Fig. 8 –Box and whisker plots of the distributions of fine (top)and coarse (bottom) zinc across the Asian region.

ig. 9 –Box and whisker plots of the distributions of fineulfur across the Asian region.

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light absorbing carbon using standards of carbon with knownareal mass density. However, it is not certain that the carbonin the atmosphere of these various locations necessarily hasthe same light absorbing capacity as the standard materials(Taha et al., 2007). Recent studies have shown that the“blackness” of the deposit depends on location particularlywith respect to distance to traffic and the sources of theparticles (Jeong et al., 2004). Thus, there may be significantdifferences in the mass absorption coefficients from locationto location so there is considerable uncertainty in the relativemagnitudes of the BC values across the region.

3.1.2. LeadFig. 7 shows themeasured distributions of lead for the fine (top)and coarse (bottom) particle fractions. Not all of the countriesare represented in this plot because as noted above, INAAcannot determine lead. Much of the lead in these countries wasdue to emissions from motor vehicles burning fuel containingtetraethyl lead. However, all of the countries reporting composi-tion data have now phased lead out of the gasoline. The motor

Fs

Fig. 10 –Time series of box and whisker plots for fine particle mass, BC, Pb, and Zn at the AEC site in Dhaka, Bangladesh.

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vehicle particles are in the submicron size range. However, theycan becomemixed with road dust andmove into super micronsize range. Thus, the lead in the coarse mode fraction is oftenfrom road dust that has been re-suspended by the motion oftiresover the roadsurface.TheUShasanairquality standard forlead in total suspended particulate matter of 1.5 µg m−3 as aquarterly average value. Bangladesh eliminated leaded gasolinein 1999 (Biswas et al., 2003), but relatively high concentrationscanbeseen in the figureshowing that other lead sources suchasbattery recycling plants play an continuing role in elevated leadconcentrations (Begum et al., 2004). Other countries are alsoremoving lead from gasoline. Australia eliminated leadedgasoline over a 4 year period terminating all sales in January2001. Indonesia eliminated the last of leaded gasoline use inJune 2006.

3.1.3. ZincFig. 8 shows the measured distributions of zine for the fine(top) and coarse (bottom) particle fractions. In most of theparticipating countries, there is extensive use of two two-stroke motor vehicles. In a two two-stroke engine, oil ismixed with the fuel to provide lubrication for piston in thecylinder. Thus, a significant amount of oil is combusted withthe gasoline. In many cases, the vehicles come with anautomatic feed system to provide a regular flow of oil into thegasoline. However, when this system breaks, owners oftenmake their own mixtures and may add more than theminimum amount of required oil. The oil contains additivesthat include zinc compounds such as zinc dialkyl(diaryl)dithiophosphate that increase its lubricating capability.When the oil is burnt along with the fuel, this zinc is released

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and is often observed as the white smoke coming from theengine exhausts.

Zinc is also emitted from municipal solid waste, galvaniz-ing operations, and non non-ferrous metal smelting. All ofthese sources contribute to the fine fraction. However, the twotwo-stroke emissions can provide substantial zinc contribu-tions to the urban street dust and thus, also be found in thecoarse fraction.

3.1.4. SulfurSulfur in airborne particulate matter is generally presentbecause of the atmospheric conversion of SO2 to sulfate throughhomogeneous processes. Thus, in general, only a portion of theparticulate sulfate is the result of local sources because there isinsufficient time to permit substantial conversion. Gas toparticle process also produces fine particles which can betransported over long distances. Fine particle sulfur can thenbecome a trans-boundary pollutant issue depending on thelocation of the major sources. Because neutron activation doesnot determine sulfur, there is again limited data within thisproject. Fig. 9 shows themeasured distributions of sulfur for thefine particle fractions. In general, sulfur is a smaller fraction ofthe fine particle aerosol composition than is commonlyobserved in the United States and Europe.

3.2. Variations in concentrations with time

The RCA, UNDP, and IAEA have supported a series of projectssuch that some countries have a longer time series of data.These data help to demonstrate the effect of changingregulations designed to improve air quality. Fig. 10 showsthe time series of box and whisker plots for fine particle mass,black carbon, lead and zinc measured at a site in Dhaka,Bangladesh. Bangladesh banned the use of leaded gasoline in1999 (Biswas et al., 2003) and then removed two-stroke, threethree-wheel taxis from Dhaka streets in 2003 (Begum et al.,2006). It can be seen that there have been substantialdecreases in the mass and species concentrations over thisperiod. The effect of phasing lead from gasoline can also beseen in the time series of data from Australia. As otherlocations develop long term time series of data, the effect ofregulatory actions can be assessed based on data related tospecific source types.

4. Conclusions

It is difficult to compare these results with the limited datathat are available in the literature. Most other reported dataare for total suspended particles that is typically the regulatoryindicator rather than PM2.5, PM10–2.5, or PM10. Because of thesignificant quantity of mass in sizes larger than 10 µm, TSPconcentrations tend to be very high in the large cities of Asia.From the results presented here, most of the countries apartfrom Australia and New Zealand would be in violation of theUS annual average standards, and many also would violatethe 24-hour ninety-eighth percentile standard. These loca-tions have various problems, including burning of biofuels forcooking and homeheating that leads to high concentrations offine PM and black carbon. Many of these countries are finally

phasing lead out of motor fuels, but the widespread use oftwo-stroke engines produces significant contributions to thefine PM. Extensive efforts by agencies such as the World Bankand the Asian Development Bank are starting to have animpact on the particle concentrations in several locations, butmore attention is needed to address the currently highconcentrations seen across the region.

Acknowledgment

This project was supported by the International Atomic Ener-gy Agency.

Appendix A. Supplementary data

Supplementary data associated with this article can be found,in the online version, at doi:10.1016/j.scitotenv.2008.05.039.

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