POLLUTIONA Comparative Analysis of Thailand, Mexico, and the United States

Household Transportation Use and Urban Air

By Roger-Mark De Souza

This report benefitedfrom the contributions of many individuals. Firstand foremost, I wish tothank the teams that conducted and wrote theinitial case studies. Theteams included AphichatChamratrithirong,Pramote Prasartkul,Sureeporn Punpuing,Wathinee Boonchalaksi,and Thirapong Santiphopfrom the Institute forPopulation and SocialResearch at MahidolUniversity in Thailand;José Luis Lezama, SilviaLuna Santos, Fortino Vela Peón, and AdrianaOropeza Lliteras from theCenter for Demographicand Urban DevelopmentStudies at the Colegio deMéxico in México; and

Edmund Egan, PeterBonner, Amy Clemons,and Jonathan Cohen fromICF Kaiser International,Inc., in the United States.

I also recognize theefforts of Hamdou-RabbyWane and his colleaguesat the Center for AppliedResearch on Populationand Development (CERPOD) for theirefforts to have Maliincluded in the study.

External reviewers con-tributed their time anduseful advice to thereport. Special thanks toJim MacKenzie (WorldResources Institute); Sara Curran (PrincetonUniversity); SureepornPunpuing (MahidolUniversity); and Alex de Sherbinin (WorldConservation Union). An earlier version of this

A C K N O W L E D G M E N T Sreport was reviewed byWolfgang Lutz (IIASA) atthe 1999 annual meetingof the PopulationAssociation of America.

Many colleagues havehelped with this project. I am indebted to Alex deSherbinin for his initialinvolvement in the pro-ject. Two colleaguesdeserve special mention:Alene Gelbard andRhonda Smith. They bothprovided vital guidanceand support at criticalstages. I am also gratefulto Peter Donaldson,PRB’s president, for hissupport, enthusiasm, andreview at various stages ofthe project.

Other colleagues pro-vided valuable support. Inparticular, I would like tomention Kimberly Crews

and Karen Semkow.Finally, I thank PRB’spublications team, particularly AllisonTarmann, Rebecca Silvis, Sara Adkins-Blanch, Donna Clifton,and Ellen Carnevale fortheir assistance in editing,production, distribution,and outreach.

I gratefully acknowl-edge the John D. andCatherine T. MacArthurFoundation and the U.S.Agency for InternationalDevelopment for theirfunding of the countryanalysis and this finalreport.

Roger-Mark De SouzaCoordinator, Population andEnvironment Programs September 1999

POLLUTIONA Comparative Analysis of Thailand, Mexico, and the United States

Household Transportation Use and Urban Air

By Roger-Mark De Souza

MAHIDOL UNIVERSITYThailand

COLEGIO DE MÉXICOMéxico

ICF KAISER INTERNATIONAL, INC.U.S.A.

POPULATION REFERENCE BUREAU1875 Connecticut Avenue, NW, Suite 520Washington, DC 20009 U.S.A.

Tel.: (202) 483-1100Fax: (202) 328-3937E-mail: popref@prb.orgWeb site: www.prb.org

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In the last half of thiscentury, the number ofpeople living in cities has more than doubled.Because of this growth,the demand for trans-portation within cities hasincreased substantially. Yettransportation networksthat often increase qualityof life, may also constraineconomic productivity,cause air pollution, anddamage people’s health.

Household Transporta-tion Use and Urban AirPollution examines thisrelationship among popu-lation, transportation, and urban air pollution.The analysis sheds light on ways that cities couldexpand transportation services in a way that min-imizes air pollution andmaximizes economicdevelopment.

PRB’s Coordinator ofPopulation and Environ-ment Programs, Roger-Mark De Souza, and

researchers from Thailand,Mexico, and the UnitedStates conducted thestudy using innovativemethodology. They com-bined statistical analysis ofnational data sets withqualitative approaches toexamine (1) the impact ofhousehold transportationuse on urban air pollu-tion, (2) how varioushousehold characteristicsaffect impact, and (3) citydwellers’ and policymak-ers’ attitudes toward pol-lution and transportationchallenges. By clarifyingthe social and economiccontexts in which con-sumption aspirations areformed, the researchersgive policymakers insightto explore measures thathave the greatest chancefor success in reducing airpollution without sacrific-ing equitable economicopportunities.

This work was madepossible with fundingfrom the John D. andCatherine T. MacArthur

Foundation and the U.S.Agency for InternationalDevelopment. PRB valuesthis support and appreci-ates the hard work andcollaborative spirit of the research teams thatworked on this analysis.We hope that this studywill inform policy deci-sions in the case-studycountries and elsewhereand lead to further policy-relevant research on link-ages between populationand the environment. We at PRB will continueto address the crucialissues related to popula-tion and the environment.More information on our efforts to do so can be found on our Web site:www.prb.org.

Peter J. DonaldsonPresidentPopulation Reference Bureau

F O R E W O R D

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Population Dynamics, Transportation, and Urban Air Pollution:

Introduction and Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Policy Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Background Note: International Conferences on Population,

Transportation, and Air Pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

APPENDICES

1. Country Teams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 2. Notes on Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263. Case Study Summaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

FIGURES

1. Map of Participating Countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42. A Glimpse at the Cities Included in the Study . . . . . . . . . . . . . . . . . . . . . . .63. Number of Motor Vehicles per 1,000 People, 1997 . . . . . . . . . . . . . . . . . . .7

BOXES

1. Air Quality in Bangkok, Mexico City, and Washington, D.C. . . . . . . . . . . .9 2. Notes on Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113. Methodology: Challenges and Lessons Learned . . . . . . . . . . . . . . . . . . . . .134. The Perceived Effects of Urban Air Pollution . . . . . . . . . . . . . . . . . . . . . . .155. Measures Recommended in the Case Studies . . . . . . . . . . . . . . . . . . . . . . .176. An Ideal Form of Transportation—Perspectives From Mexico City . . . . . .187. Potential Results: Public Education and Community Participation . . . . . . 19

T A B L E O F C O N T E N T S

FIGURE 1. Map of Participating Countries

Mexico Thailand United States

Population(in millions) 99.7 61.8 272.5

Percent urban 74 31 751998

Percent urban 82 39 852030

Urban growth rate 1.89 2.33 1.06 1995-2000

Sources:Population: Population Reference Bureau, 1999 World Population DataSheet (Washington, D.C.: PRB, 1999); percent urban 1998: PopulationReference Bureau, 1999 World Population Data Sheet (Washington, D.C.:PRB, 1999); percent urban 2030: United Nations, World UrbanizationProspects, 1996 Revision (New York: UN, 1998); urban growth rate 1995-2000: United Nations, Urban and Rural Areas 1996 Wallchart (New York:United Nations, 1997).

BANGKOK, THAILAND

MEXICO CITY,MEXICO

WASHINGTON, D.C., UNITED STATES

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This report presentsthe results of a compara-tive case-study analysis ofthe impact of householdtransportation use onurban air pollution. Thecase studies were conduct-ed in three cities that areknown to have severetransportation-relatedproblems: Bangkok,Mexico City, andWashington, D.C. Be-cause these cities representdiverse economic, cultural,political, historical, anddevelopmental contexts,the case studies provideinteresting comparisonsfor understanding con-sumption and environ-mental linkages.

Teams of scientistsfrom collaborating institu-tions analyzed nationallyrepresentative surveys tofind trends regardingtransportation, householdexpenditure, and air pollu-tion. The teams supple-mented this analysis withfocus group interviews to

determine consumer atti-tudes and intentions, andwith in-depth interviewswith policymakers toexamine policy con-straints. The researcherswanted to see what theycould garner from infor-mation on householdtransportation behaviorthat would aid in develop-ing policies to reduceurban air pollution.Specifically, they sought tounderstand the environ-mental impact of con-sumption patterns amongdifferent types of house-holds—for example,households that differ insize, average householdincome, and the gender ofthe head of household. Inaddition, they wanted toknow how much those liv-ing in urban areas knewabout the impact of trans-portation on air pollutionand whether that knowl-edge affected choicesabout what mode of trans-portation to use.

E X E C U T I V E S U M M A R YWhat did the research

teams find? Their casestudies revealed that vari-ous structural and behav-ioral factors influenced thecontribution to urban airpollution. High incomeand education levels, usu-ally associated with maleheads of households,translated into increasedhousehold pollution levels.Larger households generat-ed more pollution. Andattitudes of individualismand consumerism con-strained action that couldreduce urban air pollution.

With these factors inmind, the research teamsmade four recommenda-tions for reducing trans-portation-induced air pol-lution. All three countryanalyses suggest combin-ing improvements in thepublic transportation sys-tem with regulations andincentives to encouragethe use of less-polluting or

nonpolluting alternatives.They also recommend thatpolicies be tailored bysocioeconomic group andgender to combat specificpolluting behavior. Theanalyses reiterate theimportance of educatingthe public about theimpacts of transportationchoices on the environ-ment, and of using thatawareness as a basis forencouraging communityaction in developing andusing less-pollutingoptions. Finally, based onthe experience in this pro-ject, the country analysesurge that urban pollutionbe examined from a multi-disciplinary perspective sothat demographic andother relevant factorsinform policy decision-making.

Little internationallycomparative research hasbeen conducted on house-hold consumption pat-terns and consumer aspirations, and on howthese may affect the environment. This studyexamines current con-sumption levels and con-sumer aspirations in threecities: Bangkok, MexicoCity, and Washington,D.C. (see Appendix 1 forcountry teams).* Thesecities represent economic,demographic, cultural,and ecological diversity.This diversity providesinteresting insights (seeFigure 2). To establish the context in which theseinsights come into play,this introduction high-lights current and futureurbanization and motor-ization trends; traces

the environmental, health,and social effects of thesetrends; and outlines howthe research was designedto examine the impact of these trends (see p. 22for a glossary of termsused).

URBANIZATION AND MOTORIZATION

As much as 90 percentof future populationgrowth is expected tooccur in cities.1 This shifttoward urban areas willimprove quality of life

by bringing more peoplewithin reach of health careand education services, yet urbanization also willimpose costs. For example,with urbanization willcome the need for morehousing and transporta-tion services, the provisionof which will have envi-ronmental, health, andsocial consequences (see p. 20).

Motorization—in par-ticular the ownership ofautomobiles—rises sharplyin response to urbaniza-

P O P U L A T I O N D Y N A M I C S , T R A N S P O R TINTRODUCTION AND BACKGROUND

* Originally Mali was includedin the study, but because of diffi-culties with data, it had to beexcluded from the analysis.

FIGURE 2. A Glimpse at the Cities Included in the Study

Mexico City Bangkok Washington, D.C.

Population 1995 16,562 6,547 3,685 (in thousands)

Growth rate1995-2000 1.81 1.96 1.27

Average household size 4.7 4.5 2.26

Sources:Population 1995 and growth rate 1995-2000: United Nations, World UrbanizationProspects, 1996 Revision (New York: UN, 1998); average household size: UN Centrefor Human Settlements, An Urbanizing World (New York: UN, 1996) and U.S. CensusBureau, Statistical Abstract of the United States 1998 (Washington, D.C.: U.S.Department of Commerce, 1998).

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holds, which often includemore than one child orextended family members,depend on the car becauseof limited public transportoptions. At the same time,rising household incomeshave increased vehicleownership and led toheightened travel and adrop in public transporta-tion use.

The rise of female-headed households, how-ever, is one demographicpattern that does not seemlikely to increase motoriza-tion. Such householdscomprise more than one-

tion. In view of projec-tions on the growth of theurban population, WorldBank analysts estimate thenumber of motor vehiclesworldwide could growfrom 580 million in 1990to 816 million by 2010.2

Increased ownership ofautomobiles drives up airpollution. Cars are someof the worst air polluters:The transportation sector,which is dominated bymotor vehicles, con-tributes 30 percent of allgreenhouse gas emissions.3

Moreover, the cities poisedfor greatest growth in carownership are in countrieswhere stringent environ-mental controls often arelacking.

Data for this decadeshow that most motorvehicles are in the world’swealthy regions. In 1994,for example, 81 percent of the world’s automobileswere found in the devel-

oped countries of theOrganization forEconomic Co-operationand Development(OECD).4 The UnitedStates had one of the high-est household concentra-tions. Almost 60 percentof U.S. households ownedtwo or more cars, and 19percent owned three ormore.5

In the developingworld, car ownership ratesare far lower. In 1994,they ranged from an aver-age of 64 cars per 1,000residents in Latin Americaand the Caribbean, to 15cars per 1,000 residents inAsia, to 13 cars per 1,000residents in Africa.6 WorldBank figures for 1997show that average motorvehicle ratios in the threecountries under study con-form to the above patterns(see Figure 3). For most ofthe developing countries,primary cities will drawthe largest concentrationof vehicles. Mexico Cityand Bangkok already con-

tain about 50 percent oftheir respective countries’automobiles.

Foremost among thefactors behind the urban-ization and motorizationtrends discussed above aredemographics. Morehouseholds, changinghousehold structure, andincreasing householdincomes have led to a risein the number of cars.7

The effect of householdsize varies. In some cases,large household size mayhave a greater effect on airpollution. In other cases,growing numbers of smallhouseholds can lead tomore pollution. In general,falling average householdsizes have meant greaternumbers of urban house-holds. These householdsusually are home to theelderly, single adults, orcouples, who rely on cars for convenience andsecurity. Suburban house-

A T I O N , A N D U R B A N A I R P O L L U T I O N : FIGURE 3. Number of Motor Vehicles per 1,000People, 1997

Source:World Bank, 1999 World Development Indicators (Washington, D.C.: The World Bank, 1999).

Motor vehicles include cars, buses, and freight vehicles, but do not include two-wheelers.

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demand for cars, while atthe same time the increasein cars makes it easier toexpand cities. Since the1950s, for example, thedistribution of residentialareas and workplaces inBangkok has spilled overthe city’s boundaries intoseveral adjacent provinces.Because new and popularhousing estates are increas-ingly located far from the center of Bangkok,they lead to longer com-mutes and ultimately tohigher levels of vehicularemissions.

A third factor is therelative cheapness of cars,especially in developedcountries, compared withland. This cost differentialmotivates households tobuy low-priced housing inurban peripheries, eventhough living thererequires more travel. Highland prices in Bangkoknot only encourage rela-tively well-off residents tosell and relocate in new,less central areas of theBangkok metropolitanarea, but also force inner-

city slum dwellers toperipheral locations. Thesedevelopments lead toincreasingly lengthy com-mutes in Bangkok and its environs.

INCREASINGMOTORIZATION ANDITS ENVIRONMENTAL,HEALTH, AND SOCIAL IMPACTS

Environmental ImpactOne result of increas-

ing motorization is morefuel consumption, whichincreases pollution. Whencar dependence increases,fuel consumption risesexponentially because ofgrowing road congestion,vehicles that use fuel inef-ficiently, and poor vehicleand road maintenance.Globally, 20 percent of allenergy produced is used

for transportation. Of this,between 60 percent and70 percent is devoted tomoving people, and therest to moving freight.9

Transport-related energyconsumption is expectedto grow in both the devel-oped and the developingworld. From 1971 to1992, worldwide energyuse in the transportationsector grew on average 2.7percent per year, fasterthan in the industrial orother sectors.10

Recent World Bankestimates suggest thatenergy demand in low-and middle-income coun-tries, now one-third ofenergy demand in OECDcountries, will matchdemand in OECD coun-tries by the year 2015.11

Bangkok is alreadyplagued with notoriously

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fifth of all householdsworldwide, and researchhas shown that they focustheir spending on nutri-tion and education, noton private transportation.These households maytherefore use more publictransportation facilities, ifavailable.8

A second key factorinfluencing the number ofcars is city design. Sprawl-ing cities increase the

In 1994, almost 60 percent of U.S. households owned two or more cars.

Vehicles emit greenhouse gases that contribute to smog.

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high levels of air pollutionand congestion, despitelow motor vehicle owner-ship per capita (72 vehi-cles for every 1,000 resi-dents) compared withmany developed cities(500 per 1,000 residentson average). In addition,an average car in Bangkokis estimated to spend theequivalent of 44 days peryear stuck in traffic.12 Evenso, 300 to 400 more vehi-cles are being added to the streets of Bangkokevery day.

The connectionbetween vehicle emissionsand global warming isbecoming increasinglyclear (see p. 20). Vehiclesemit carbon dioxide,nitrous oxide, and carbonmonoxide, which arereferred to as greenhousegases because they maycontribute to global warm-ing. In the United States,transportation sources areresponsible for significantamounts of these gases as

well as other ambient pol-lutants. In 1997, forexample, they accountedfor 77 percent of carbonmonoxide emissions, 49percent of nitrogen oxides,40 percent of volatileorganic compounds, and24 percent of particu-lates.13 However, the shareof emissions from develop-ing countries is expectedto rise in the futurebecause of the growingsize of their motor vehiclefleets and their use of less-efficient fuel-burning tech-nologies. In these coun-tries, automotive air pollu-tion is mostly a problemin large cities with highlevels of traffic, such asMexico City and Bangkok(see Box 1).

Health ImpactThe health threats

posed by transportationdepend on the levels ofthree pollutants: suspend-ed particulate matter(SPM), carbon monoxide,and lead. SPM is made upof molecules suspended in

the air. Small molecules ofSPM, less than 10 micronsin diameter, are more dan-gerous than large onesbecause they may enterthe respiratory system.Small molecules of SPMare found in smoke fromdiesel engines, burning,cigarettes, and some kindsof industrial activity.Inhaling SPM causes aller-gic reactions and respirato-ry diseases, and SPM inbig cities contains cancer-related components.Rough estimates indicatethat, if unhealthy levels ofSPM were reduced to theaverage yearly level thatWHO considers safe,between 300,000 and700,000 premature deathsa year would be avoided indeveloping countries.14

Carbon monoxide, a colorless, odorless, andtasteless gas, is anotherpollutant hazardous tohuman health. It is pro-duced from incomplete

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Box 1 Air Quality in Bangkok, Mexico City,and Washington, D.C.

According to a 1992 analysis by the World Health Organization (WHO) and the United NationsEnvironment Programme (UNEP), levels of suspendedparticulate matter in the air in Bangkok exceeded WHOhealth safety guidelines by more than a factor of 2, andlevels of airborne lead exceeded guidelines by up to afactor of 2. Even though the level for carbon monoxidewas low, in its case study the Thai research team citedmedia coverage indicating that carbon monoxide emis-sions were associated with a number of cases of respi-ratory and heart diseases, headaches, and dizziness,and with a three- to five-point I.Q. decrease among 7-year-olds.

Mexico City’s air quality was poor: Levels of sus-pended particulate matter and carbon monoxide ex-ceeded WHO health safety guidelines by more than afactor of 2, and levels of airborne lead by up to a factorof 2. The bad air quality is exacerbated by the largenumber of old and poorly maintained vehicles in the cityand by poor air circulation caused by the city’s high alti-tude and climate.

In the United States, the Environmental ProtectionAgency (EPA) uses six “criteria pollutants” as indicatorsof air quality. The EPA has established a maximum con-centration for each of them, above which adverseeffects on human health may occur. The number of daysin a year for which the Washington, D.C., region hasexceeded these levels has fallen since the 1980s, from17 days in 1985 to 7 days in 1994.

Sources: UNEP/WHO, Urban Air Pollution in Megacities of theWorld (Oxford: Blackwell Publishers Ltd., 1992); Country CaseStudies; and EPA, National Air Quality and Emissions TrendsReport, 1997 (Washington, D.C.: EPA, 1998).

of their income on publictransport than do mem-bers of wealthy house-holds. And in householdbudgets, the cost of thebreadwinner’s trip to work may be the top pri-ority, sometimes meaningthat trips for schooling or health services are sacrificed.16

With increasing popu-lation growth and growingeconomic activity, thechallenge for cities is todevelop more efficienttransportation systems—systems that manageurban travel demand with-

out degrading the qualityof life. One way to meetthis challenge is to consid-er the potential pollutionimpact of consumer inten-tions. This study looks atthese intentions and exam-ines their policy and pro-gram implications.

RESEARCH DESIGN

The research teams soughtto answer three questions*:

1. How does consumptionvary among households ofdifferent sizes with differ-ent demographic charac-

combustion in vehiclesusing gasoline. Incompletecombustion occurs whenthe ratio of air to fuel isless than 14:1 or whenthere is a clotted filter.Inhaled carbon monoxidetemporarily incapacitateshemoglobin, causes dizzi-ness, and constitutes a

danger for patients withheart disease.

Motor vehicles alsocontribute significantly toemissions of lead, the thirdkey pollutant. An estimat-ed 80 percent to 90 per-cent of lead in ambient airis derived from the com-bustion of leaded gasoline.When inhaled or ingested,lead attacks the systemthat produces hemoglobinand may lead to anemia

and nervous disorders,especially in children.Recognizing the healththreat, most developedcountries have reduced the lead content of gaso-line over the past decade.In most cities of the devel-oping world, however,ambient lead levels stillgreatly exceed the WHOstandard of 1 microgramper cubic meter.15

Social ImpactIn addition to the

threats to the environmentand to human health,urban transportationtrends also raise equityquestions. In cities wherelarge segments of low-income groups live in theperiphery of the urbanarea, questions of isolationand inaccessibility arisebecause opportunities foremployment, advancededucation, recreation, andshopping are often locatedin the city center.Members of poor house-holds, for example, mayspend a larger percentage

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*See Appendix 2 for details onmethodology.

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teristics—such as income,age, and gender?

2. What are the environ-mental implications ofcurrent household con-sumption patterns, partic-ularly those related totransportation use?

3. What is the level ofawareness of the linksamong household size,consumption, and the environment, and howcould this awareness shape strategies to reduceair pollution?

Box 2 Notes on Methodology

The research for the case studies was done in twostages. In the first, the quantitative stage, teams of nat-ural and social scientists analyzed household incomeand expenditure data from nationally representativesurveys for each country. These data allowed theresearchers to examine household expenditure pat-terns and levels of transportation use for groups withdifferent demographic characteristics and income lev-els. Using these data, researchers developed estimatesfor implied environmental impact of household-leveltransportation use.

In the second stage, researchers formulated focusgroup interview guides that served as the basis for thequalitative analysis. Each research team targeted dif-ferent socioeconomic groups of the urban populationand conducted focus group interviews to determine:■ current consumption levels; ■ aspirations to future transportation use; and ■ perceptions of the linkages between individuals’transportation choices and impact on the environmentand human well-being, paying special attention to airpollution.

For Mexico City and Bangkok, in-depth interviewswith policymakers supplemented focus group data. Appendix 3 contains country data sources.

The teams decided tofocus on one particularindicator of consumptionpatterns—transportationuse—because of transport’seconomic, environmental,and social consequences,and because congestionand associated transporta-tion problems are perva-sive in these cities.

For the case studies,teams conducted bothquantitative and qualita-tive research, using meth-ods they developed (seeBox 2). The quantitativeanalysis aided in determin-ing statistically significant

impacts of demographiccharacteristics on trans-portation consumptiondecisions. The qualitativeanalysis helped theresearch teams elicit fromthe residents of the threecities under study theirattitudes and perceptionsregarding the extent andcauses of environmentalpollution and their futureconsumption intentions.

To examine house-holds’ direct and indirecteffects on transportationuse, the teams viewedhousehold variables as amultiplier of the effects ofother factors that influencetransportation use. Theresearchers linked house-hold variables, transporta-tion use, and air quality byusing a simple causalmodel to incorporate andaccount for the effects ofother factors such associoeconomic changesand changes in technology.

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This section highlightsthe lessons of special in-terest from the countrystudies. The case studiesthemselves describenational trends in broadterms, then report on individual findings (casestudy summaries appear inAppendix 3, p. 28). Thequantitative and qualita-tive work suggest that several structural andbehavioral factors deter-mine the level of impacthouseholds have on urbanair pollution (see Box 3for lessons on using thismethodology).

STRUCTURALFACTORS THATCONTRIBUTE TO URBAN AIRPOLLUTION

Quantitative analysisby the research teams ofhousehold-level datapointed to structural

factors that influence air pollution. These factors are essentially householdcharacteristics such ashousehold size and thesocioeconomic status and gender of the house-hold head.

As income and educationrise, the level of pollution

generated by the householdrises. The case studies confirm the detrimentaleffect of higher socioeco-nomic status on pollution.In Bangkok, white-collarhousehold heads producedbetween 3.7 kilograms and4.6 kilograms more ofSPM per year than thosewho worked in the salesand service or productionsectors. At the same time,an increase of 1,000 baht(about U.S. $26 at currentrates) in monthly incomeled to a 0.1-kilogramincrease in emissions per year. In Washington,D.C., people on averagespent more on both gaso-line and public transporta-tion with additional

income and education.Elderly households withhigher income tended tospend more money on private travel. One-parenthouseholds tended tospend far more than two-parent households on pub-lic transportation. InMexico, every additionalyear of formal educationof the household head waslinked to production of

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vation: Car ownership was less common amongfemale-headed householdsthan among male-headedhouseholds, meaningfemale-headed householdsrelied more on publictransportation, and thenumber of female-headedhouseholds in Mexico Citywas quite large.

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Box 3 Methodology: Challenges and Lessons Learned

In this project, the research teams debated how to measure household transportation’s impact on the environment. They decided to focus on expenditures,using them as a proxy for implied pollution impact. Because of this approach, the models that the research teams used do not predict travel behavior per se—that is,the decision to drive or to use public transportation. If the price of gasoline were to drop significantly, for example, one might observe a change in these relationships in the direction of greater public transportation expenditure, while the householdcould in fact be driving more than before. In spite of this limitation, the teams believe that, in the given timeframe, expenditures gave valid insight into householdtransportation use.

Data availability provided an additional challenge. The data sets on householdincome were selected on the basis of accessibility—that is, whether the data set was in the possession of one of the collaborating institutions or could be easilyobtained. In addition, expenditure survey data for each country were selected based on the inclusion of household expenditure data. This was one of the greatest challenges for some of the researchers. In the final analysis, a research team fromMali, which was originally part of the project, had to be omitted from the studybecause of difficulty with appropriate data.

In some regards, this project was an experiment to test the efficacy of combiningquantitative and qualitative methodologies to examine population-environment issues.This approach was difficult and rewarding. It was difficult because it was time consuming, required much planning and preparation, and was new for many of theresearchers. Yet the additional insight it provided helped inform the policy recom-mendations and put a human face on the research questions. The strength of thisapproach lies in its relatively low cost (relative to polls or large-scale surveys), flexibility (the ability of focus group leaders to guide discussion based on the interestsof participants), and originality (the possibility of turning up new or unanticipated findings that might not be elicited by a more rigid survey instrument). According toDebus (1991), one of the best uses of the focus group is to help understand the resultsof a quantitative study, in particular to understand the reasons for an unexpected finding, to gain some understanding about the reasons for certain trends, and todescribe factors effecting an attitudinal change. The research teams believe that thefocus group approach served these purposes in this research.

Appendix 3 contains further details on methodology.

hat one

person can do

makes a

difference.

One person not

driving reduces

pollution.

Low-income focus group participant, Washington, D.C.

“W

”

approximately 0.7 kilograms of SPM, 98kilograms of carbonmonoxide, 24 kilogramsof hydrocarbons, and 126kilograms of total emis-sions per year.

Male-headed householdsengage in more polluting

behavior than female-headedhouseholds. The case studiesprovide interesting insightinto the effect of the gen-der of the household head.In Bangkok, male-headedhouseholds emitted about2.7 more kilograms ofSPM per year than female-headed households did.Similarly, in Mexico City,male-headed householdshad a major impact onpollution per capita,regardless of the kind oftransportation used bymembers. However,spending on public trans-portation by female-head-ed households in MexicoCity also had a detrimen-tal impact on air pollu-tion. Two factors wereresponsible for this obser-

2

Large households spend more money on

transportation and, as a result,generate more pollution. Notsurprisingly, the case stud-ies illustrate that house-hold size is an importantvariable. In Bangkok,extended families pro-duced about 5.3 morekilograms of SPM per yearthan one-adult householdsdid, and nuclear familiesproduced about 3.5 morekilograms. In Washington,D.C., two-parent house-holds tended to spendmore on private trans-portation than smallerhouseholds, and their

14

average total transporta-tion expenditures werehigher as well. Elderlyhouseholds spent less thanother types of householdson total transportation,but their expenditureswere also heavily biasedtoward private transporta-tion. One-parent or one-adult households, in contrast, tended to dividetheir expenditures moreequally between publicand private transport.

The contribution to pol-lution was higher amongWashington, D.C., households that used public transport thanamong those that did notuse public transportbecause the former hadlarger households. InWashington, on average,two-parent householdsspent the greatest amounton private (automobile)

transportation, while one-parent households spentthe most on public trans-portation.

BEHAVIORALFACTORS THATINCREASE URBANAIR POLLUTION

The qualitative analysisallowed the research teamsto further explore whyurban dwellers make thetransportation choicesthey make. Behavioral fac-tors center on attitudes of

“…we look for convenience. So, we buy a car. We know that when our car is added, the traffic would increase… but the traffic would be already congested if our car hadn’tbeen added.” Middle-income focus group participant, 18-to-29 age group, Bangkok

3

Many Thai families rely on

motorcycles for their

transportation needs.

© 1994 PETER MENZEL/MATERIAL WORLD

15

Box 4 The Perceived Effects of Urban Air PollutionFocus group participants in all three case-study cities had similar perceptions of the effects of urban air pollution.■ Urban air pollution affects quality of life. Most focusgroup participants either directly identified air quality asa quality-of-life issue or established a causal relationshipbetween air pollution and other quality-of-life issues,such as illness or insecurity.■ Various health problems are related to air pollution. Onlyparticipants in Bangkok perceived air pollution as amajor threat, although participants in all three cities per-ceived some relationship between health problems andair pollution. Yet all appeared willing to accept thisimpact in the absence of evidence showing that it is amajor threat. In essence, individuals seemed to be adapt-ing to the situations imposed by the air pollution risks.Still, these participants saw air pollution as a nuisance.Medium- and high-income groups from Mexico City, forexample, spoke of the inconvenience of having to havetheir car engines inspected and of the annoyance theyfelt when the government imposed driving bans on highlypolluted days. In contrast, Bangkok participants wereparticularly sensitive to the impacts of air pollution onhealth. ■ Little information is available to the public on connec-tions between air pollution and health. Despite mountingevidence of the effects of air pollution on health, particu-larly in Bangkok and Mexico City, few participants feltthat the public was aware of the connection. Most par-ticipants thought that, if air pollution’s detrimental effectson health were proven, obvious, and widespread, theywould be more willing to change their behavior. Theynoted the effectiveness of public information and educa-tion initiatives, incentives, and legal and social pressuresapplied in anti-smoking and household recycling cam-paigns and recommended using similar tactics in theeffort to reduce air pollution.

individualism and con-sumerism, reflected partlyin the priority placed onconvenience and flexibilityin transportation options.

Individualism and consumerism hinder

action that could reduce urbanair pollution. Many focusgroup respondents felt thatBangkok’s civil societyorganizations did not yetwork together in commu-nity-driven strategic plan-ning to tackle issues thataffect their lives, such assprawl. Interestingly, most participants fromWashington, D.C., admit-ted that individual choiceswere responsible for thelevel of air pollution in thearea. Most immediatelyidentified the automobileas a major cause of air pol-lution and their decisionsto drive or not to drive ascontributing factors.However, not manyaccepted responsibility for

reducing the amount of airpollution by choosing notto drive or by changingtheir behavior in otherways. The medium- andhigh-income Mexico Cityparticipants believed thatauthorities made it appearas if cars were the majorcause of air pollution,whereas participants felt itwas not. High-incomegroups in Mexico Cityand Washington, D.C.,seemed less committed totaking personal action totackle the problems ofurban air pollution.

Although they perceivethat urban air pollution

has an adverse effect on health,many urban dwellers continue touse their cars because of conve-nience. Participants in allthree case studies indicatedthat, even though theyperceived that they mightbe contributing to air pol-lution (see Box 4), theyrelied on their cars forconvenience or to meettheir professional commit-

ments. At the same time,poor public transportationcontributed to a relianceon the private car. In thethree case studies, the useof private cars was recog-nized as one of the majorsources of air pollution.The Washington, D.C.,case study revealed that,per dollar of expenditure,automobiles on averageproduced four times moreparticulate emissions thanbuses do. In all threecities, however, car ownerswere reluctant to give upthe use of their carsbecause they believed thatpublic transportation wasinsufficiently widespread,unavailable at times theyneeded it, or unsafe.Bangkok participantsfound public transporta-tion to be slow, over-crowded, and unreliable.

1

2

© H

AR

TM

UT

SC

HW

AR

ZB

AC

H/S

TIL

L P

ICT

UR

ES

The findings of thecase studies lead to fourrecommendations for policies to reduce trans-portation-associated airpollution.

Combine improvements in the public transporta-

tion system with regulations andincentives to encourage the useof less-polluting or nonpollutingtransportation alternatives suchas walking, cycling, and tele-commuting. The variety ofsolutions suggested by theurban dwellers and policy-makers in this projectclearly indicates that thereis no single answer (seeBox 5). Reducing air pollu-tion will require a mix ofactivities including incen-tives (high-occupancy-vehicle lanes, recycling)and regulations (emissioncontrols, new technologies,and penalties).

Improving publictransport was seen asbeing of primary impor-tance. In all three casestudies, focus group par-ticipants said they woulduse public transport moreif it offered comfort, secu-rity, adequate speed, andenough routes—amongother characteristics.

Generally individuals werewilling to engage in non-polluting types of trans-port where possible.Walking, however, did notseem feasible to many, dueto the long distances thatthey traveled daily and tosafety concerns. Yet amongparticipants in the medi-um- and low-income

P O L I C Y R E C O M M E N D A T I O N S

1

“If I knew that bad air was going to affect my health in the next 20 years, if it was linked to something concrete, I might dosomething about it.”High-income focus group participant, young group, Washington, D.C.

© R

OB

CR

AN

DA

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© S

UP

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STO

CK

groups, who often usepublic transportation,walking short distancesfrom transit point to finaldestination was acceptable.

Tailor policies by socio-economic group and gen-

der to combat specific pollutingbehavior. The results of thequantitative analysis con-sistently show that thehigher the socioeconomicstatus, the greater theprobability to contributeto air pollution throughtransportation use. Thequalitative analysis showsthat willingness to partici-pate in programs to reduceair pollution also varied bysocioeconomic status (seeBox 6, p. 18, for details onMexico City). In MexicoCity and Washington,D.C., participants in high-income focus groupsexhibited a greater relianceon government to solve airpollution problems.Members of medium- andlow-income groups felt

2

Box 5 Measures Recommended in the Case Studies

Short Term■ Encourage carpooling by designating more high-occupancy-vehicle lanes, more park-and-ride spaces, and more bike paths.■ Increase public safety measures within the public transport system to reduce incidents such as robberies that discourage the use of this kind of transport. ■ Ban vehicular traffic in certain areas of the city.■ Limit parking options and strictly enforce time limits on parking meters.

Short-to-Medium Term■ Institute flexible working schedules, permitting government employees to arrive and leave earlier or later, to mitigate congestion during the rush hours. Encourage companies to adopt similar policies.

Long Term ■ Explore the possible trade-offs between information travel and human travel—for instance, telecommuting.

that individuals in theirdaily lives could do moreto reduce air pollution.Policymakers should bearin mind socioeconomicstatus when developingspecific policies and whenprojecting how those poli-cies might be received.Although the qualitativefindings were not disaggre-gated by gender, the evi-dence from the quantita-tive analysis that maleheads of household pollutemore supports a similartailoring of policies by gender.

Educate the public aboutthe impact of transporta-

tion choices, particularly on airpollution, and encourage com-munity involvement in educationefforts. The results of thefocus group analysis sug-gest that many urbandwellers are unsure aboutthe impacts of transporta-

tion use. If reliable, objec-tive, peer-reviewed scien-tific work has clearlyshown a negative impactof transportation choiceson the environment, andultimately public health,those results should be dis-seminated to the publicthrough education cam-

3

17

paigns. If such research islacking or inadequate,such studies should becommissioned (see Box 7,p. 19).

Many of the focusgroup participants did notfeel they had control over

18

their impact on air pollu-tion, yet the quantitativeanalysis clearly demon-strates that the collectiveimpact of personal choicesregarding transportationuse had a significantimpact on air pollution.Although some partici-pants believed that theaction of one individualcould influence others’actions, most thought the impact of one personwould be minimal. Groupsin Mexico City andWashington, D.C.,believed that collectiveaction by citizens couldhave an impact in thelocal area or in their par-ticular counties. Ultimately,therefore, city authoritiesshould encourage activecommunity participationin promoting nonpollut-

ing behavior, particularlyin reducing reliance on theprivate car.

Examine urban pollutionfrom a multidisciplinary

perspective so that demographicand other relevant factors informpolicy decisionmaking. Thisstudy illustrates the valueof linking demographicand environmental phe-nomena because it showsspecific effects of demo-graphic variables—such aspopulation growth, densi-ty, and distribution as wellas household size andstructure—on urban pol-lution problems.Additionally, the studyillustrates the value ofcombining quantitativeand qualitative analyses.Canvassing urban dwellersto gain insight into whatpolicies might be success-ful in addressing urbanpollution problems is asimportant as quantifying

these problems. Focusgroups helped those whoconducted this studyunderstand the behaviorthat contributes to urbanair pollution, whereasanalysis of household dataprovided insight into thestructural factors thatinfluence transportationchoices and contribute tourban air pollution.

The findings in thisstudy reveal intertwiningcause-and-effect relation-

4

Box 6 An Ideal Form of Transportation—Perspectives From Mexico City

The private car was the preferred method oftransport in the high-income group, although focusgroup participants acknowledged that traveling bycar typically means enduring traffic and strugglingto find a safe place to park. Participants mentioned, however, that they would use public transportationif it were well organized, comfortable, and couldmeet current demand. However, many participantsfeared robberies and violence and saw a lack of safety as an obstacle to using more public transportation.

Participants in the medium-income groupthought that the subway and tramway were idealtransportation for Mexico City. They said they wouldrather not have to spend money on gasoline andcould benefit from reading or sightseeing while onpublic transport. They shared the safety concerns ofthe high-income group, expressed reluctance abouthaving a subway station near their homes (sincestations are always accompanied by street sellersand the consequent dirt of the streets), and felt thatthe current subway system in Mexico City is inade-quate to cover public demand for transportation.

The low-income group favored increasing thenumber of minibuses and buses to ensure that theywere more frequent. The group suggested that largebuses should replace small buses and that the number of trams should be increased to reduce air pollution. Excerpted from the Mexico City case study

Some Mexican families favor the bus for outings.

19

ships among householdstructure and needs, citydesign, travel behavior,and pollution impacts.

In addition, there arealmost certainly strongpersonal motives for dri-ving a car, even whenother options exist anddespite the increasinginconvenience and healthrisks associated with trafficcongestion. The strongindividualism demonstrat-ed by many of the focusgroup participants, andthe perception frequently

Box 7 Potential Results: Public Education andCommunity Participation

Short term■ Mass media campaigns increase public aware-ness and a sense of mutual responsibility.■ Community groups such as schools, universities,churches, and companies encourage carpooling.

Medium term■ Reputable scientific studies make clear the con-nection between air pollution and disease. Thesestudies provide evidence that behavior change (lessdriving) can lead to health benefits (decreased inci-dence of headaches, heart attacks, lung cancer, andthe like).

Long term■ Dissemination of the results of these studiesincreases knowledge among citizens of the effectsof air pollution and leads to behavior change—self-discipline, respect for the rights of others, and awillingness to fight for protection of communityinterest.Excerpted from case studies

heard among them thatindividual action cannotaffect the environment, areimportant components ofthe persistent decision todrive in the face of moreenvironmentally healthyoptions.

Given the interplay ofthese factors, combininginfrastructure improve-ments with incentives and regulation, targetededucation campaigns, and informed multidisci-plinary study would holdthe greatest promise forreducing transportation-induced pollution.

he use of

vehicles

in our country

is due…

to necessity

and [to]…

the status

attached to it.

We have to take

these two

causes of the

problem into

consideration.

In-depth interview, male member of parliament, Bangkok

“T

”

© 1993 DML FAIRBANKS/MATERIAL WORLD

20

have focused specificallyon urban transportationissues: the 1992 UNConference on Environ-ment and Development(UNCED) held in Rio deJaneiro, the Conference ofParties (COP) meetingsheld from 1992 to thepresent surrounding theUN Framework Con-vention on ClimateChange (UNFCC), andthe 1996 UN Conferenceon Human Settlements(Habitat II) in Istanbul.Two other meetings

referred to the linkages:the International Con-ference on Population andDevelopment (Cairo,1994) recognized the linkages between trans-portation and demograph-ic variables, while theWorld Summit for Social Development(Copenhagen, 1995) situ-ated transportation in asocial policy context.

Agenda 21, UNCED’sProgramme of Action,highlights three important

points relating to urbantransportation. The first isthat there are economic,environmental, and socialcomponents to transporta-tion dynamics. The docu-ment notes, for example,that while transportationis necessary for economicdevelopment, it has nega-tive impacts, particularlyon marginalized urbangroups, through pollution,injuries, congestion, andloss of productivity.17 Thesecond point is countries’responsibility for sounddevelopment. Agenda 21states, for example, thatdeveloping countries arefaced with the need toincrease their energy pro-duction to acceleratedevelopment and raise theliving standards of theirpopulations, but at thesame time they need toreduce energy productioncosts and energy-relatedpollution. The third pointin Agenda 21 is the speci-

International Conferences With References to Household Dynamics, Pollution, and Transportation

Conference References

UN Conference on Environment and Development, 1992 Programme of Action (Agenda 21), Chapters 7 and 9

UN Framework Convention on Climate Change, 1992 to 1999 The Convention Treaty, Protocol documents from Berlin (1995), Geneva (1996), Kyoto (1997), Buenos Aires (1998) Berlin (1995), Geneva (1996), Kyoto (1997), Buenos Aires (1998)

International Conference on Population and Development, 1994 Programme of Action, Sections 3, 5, and 9

World Summit for Social Development, 1995 Programme of Action, Sections 31(a) and 34 (c)

UN Conference on Human Settlements (Habitat II), 1996 The Istanbul Declaration on Human Settlements, The Habitat Agenda, Preamble and Chapter 7

The relationshipamong transportation,urban air pollution, andhousehold dynamics cap-tures three essential com-ponents of a sustainabletransportation agenda:economic viability, envi-ronmental integrity, andsocial equity. Transporta-tion has been dealt with atinternational conferenceson sustainable develop-ment held throughout the1990s (see box below).Three of these meetings

B A C K G R O U N D N O T E :INTERNATIONAL CONFERENCES ON POPULATION, TRANSPORTATION, AND AIR POLLUTION

21

ficity of urban pollution:The document recognizesthat many metropolitanareas suffer from trans-port-related air-qualityproblems.

UNFCC, endorsed by166 countries at UNCED,also provided the basis forongoing internationalnegotiations to decide ona protocol of commit-ments to help stabilizeatmospheric concentra-tions of greenhouse gases.UNFCC built on two ear-lier global agreements. In1985, the world’s nationsagreed to take strongaction to stop depletion ofstratospheric ozone byentering into the ViennaConvention for theProtection of the OzoneLayer. This treaty wasstrengthened in 1987 bythe Montreal Protocol onSubstances that Depletethe Ozone Layer. By 1993,150 nations ratifiedUNFCC, and in 1994 thetreaty entered into force,committing industrializednations to reduce their

emissions of greenhousegases not controlled by theMontreal Protocol to 1990levels by the year 2000.18

International negotiationsare now underway amongthe UNFCC signatories todefine a protocol that willlimit emissions of thesegases after the year 2000.

Since 1995, four COPmeetings have taken placeto guide negotiations for aprotocol requiring furtheraction for the early 21stcentury. In 1995, atCOP1 in Berlin, the par-ties agreed to the so-called“Berlin Mandate,” becausethey found that developedcountries’ commitments tocurb greenhouse gas emis-sions were not adequate tomeet UNFCC’s goals. Assuch, the parties set aschedule for negotiating aprotocol to toughen thesecommitments after 1997.Around this time, new sci-entific evidence convincedparties to the MontrealProtocol to control addi-

tional ozone depleters andaccelerate the phase-out ofthose already included inthe protocol. On January1, 1996, the world’s indus-trialized countries ceasedproduction of chlorofluo-rocarbons, carbon tetra-chloride, and methyl chlo-roform (with a few essen-tial uses exempted). Laterthat year, at COP2 inGeneva, the United Statessupported a report on cli-mate change that had justbeen released by an inter-national panel of climateexperts, the Intergovern-mental Panel on ClimateChange. The UnitedStates announced that itwould support bindingtargets to reduce green-house gas emissions.

In 1997, at COP3 in Kyoto, industrializedcountries agreed to workon measures to limit orreduce transport-relatedgreenhouse gas emissionsnot controlled by theMontreal Protocol. In1997, at COP4 in Buenos

Aires, more than 160countries agreed on dead-lines and an action plan toguide efforts to fight glob-al warming. The countriesagreed to set rules forenforcing the Kyoto pactby late 2000, includingtough measures to guardagainst cheating andpenalties for countries thatfail to comply.19 Theseefforts all affect the trans-portation sector becausemany of the greenhousegas emissions are fromtransportation sources.

Habitat II, alsoreferred to as the “CitySummit,” reaffirmed theresults from UNCED andrecognized the specificimpacts of urban trans-portation problems. InIstanbul, participantsmentioned three majorelements that must beaddressed to improve thequality of life withinhuman settlements. Thesewere unsustainable con-

sumption and productionpatterns, particularly inindustrialized countries;unsustainable populationchanges, includingchanges in structure anddistribution (giving priori-ty consideration to exces-sive population concentra-tion); and environmentaldegradation.20 Habitat II’sProgramme of Action, theHabitat Agenda, recog-nizes a number of urbanproblems that directlyrelate to the transporta-tion sector. These includeincreased poverty and awidening gap between rich and poor, growinginsecurity and rising crimerates, improper land use,rising traffic congestion,increasing pollution, lack of green spaces, anduncoordinated urbandevelopment.21

22

Female-headed household. A household headed by anunmarried, divorced, separated, or widowed woman or a household headed by a grandmother or other womanwho lives alone or with other women.

Global warming. Phenomenon that occurs as a result ofthe build-up of carbon dioxide and other greenhousegases. Scientists have identified global warming as amajor global environmental threat.

Greenhouse gases. Carbon dioxide, nitrous oxide,methane, ozone, and chlorofluorocarbons that occur nat-urally, result from human (production and consump-tion) activities, and contribute to the greenhouse effect.

Habitat Conference. UN Conference on HumanSettlements. The first conference was held in Vancouver,British Columbia, from May 31 to June 11, 1976; thesecond conference was held in Istanbul, Turkey, fromJune 3 to June 14, 1996 (this conference is also referredto as the “City Summit”).

Household. Usually defined as one or more persons whooccupy a single housing unit. Households consist ofunrelated persons or persons related by birth, marriage,or adoption.

Metropolitan area. A large concentration of population,usually an area of 100,000 or more people, with animportant city at its core and suburban and exurbanareas surrounding the city that are socially and economi-cally integrated with it.

G L O S S A R YAgenda 21. The plan of action to achieve sustainabledevelopment that was adopted by world leaders at theUN Conference on Environment and Development heldin Rio de Janeiro, Brazil, in June 1992.

Air pollution. The presence of contaminant or pollutantsubstances in the air that do not disperse properly andthat interfere with human health or welfare, or produceother harmful environmental effects.

Carbon dioxide (CO2). A colorless, odorless, and nonpoiso-nous gas that results from fossil fuel combustion and isnormally a part of ambient air. It is also produced in the respiration of living organisms (plants and animals).CO2 is considered to be the main greenhouse gas contributing to climate change.

Carbon monoxide (CO). A colorless, odorless, and poiso-nous gas produced by incomplete fossil fuel combustion.Carbon monoxide combines with the hemoglobin ofhuman beings, reducing its oxygen-carrying capacity andcausing dizziness and other symptoms.

Elderly household. A household maintained by one ormore persons over age 64.

Emission. Discharge of pollutants into the atmospherefrom stationary sources—such as smokestacks, othervents, and surface areas of commercial or industrial facil-ities—and from mobile sources such as motor vehicles,locomotives, and aircraft.

23

Ozone (O3). A pungent, colorless, toxic gas that containsthree atoms of oxygen in each molecule. It occurs naturally at a concentration of about 0.01 parts per mil-lion (p.p.m.) of air. Levels of 0.1 p.p.m. are consideredto be toxic. In the stratosphere (or upper layer of theatmosphere), ozone provides a protective layer shieldinghuman beings and other living organisms on Earth fromthe harmful effects of ultraviolet radiation. In the tropos-phere (layer of atmosphere extending about 10 kms.upward from Earth’s surface), ozone is a major compo-nent of photochemical smog, which seriously affects thehuman respiratory system.

Population density. Usually expressed as the number of people per unit of land area.

Population policy. Explicit or implicit measures institutedby a government to influence population size, growth,distribution, or composition.

Quality of life. Notion of human welfare (well-being).Quality of life is measured by social indicators ratherthan by quantitative measures of income and produc-tion.

One-adult household. Household that does not containchildren and is maintained by one adult.

One-parent household. Household that contains childrenand is maintained by one parent as a result of an out-of-wedlock birth, divorce, separation, or the death of aspouse.

Smog. Combination of smoke and fog in which productsof combustion such as hydrocarbons, particulate matter, and oxides of sulfur and nitrogen occur in concentrations that are harmful to human beings andother organisms.

Suspended particulate matter (SPM). Finely divided solidsor liquids that may be dispersed through the air fromcombustion processes, industrial activities, or naturalsources.

Two-adult household. Household that does not containchildren and is maintained by two adults.

Two-parent household. Household that contains childrenand is maintained by two parents.

Urban population. The population living in urban areas.Countries differ in the way they classify population asurban or rural. Typically, population living in a commu-nity or settlement with 2,000 people or more is consid-ered urban.

Sources: United Nations, Glossary of Environmental Statistics, 1997;PRB, Population Handbook, International Edition, 1998; UN Centrefor Human Settlements, An Urbanizing World (New York: UN,1996): 12.

1. Robert Livernash and Eric Rodenburg, “PopulationChange, Resources, and the Environment,” PopulationBulletin, vol. 53, no. 1 (Washington, DC: PopulationReference Bureau, March 1998): 12.

2. Asif Faiz and Surhid Gautam, “Motorization,Urbanization, and Air Pollution,” discussion paper(Washington, DC: The World Bank, 1994).

3. Livernash and Rodenburg, “Population Change”: 18.

4. Computed based on the American AutomobileManufacturers Association’s World Motor Vehicle Data 1996(Detroit: AAMA, 1995).

5. Patricia S. Hu and Jennifer R. Young, Summary of TravelTrends: 1995 Nationwide Personal Transportation Survey,Draft (Oak Ridge, Tenn.: Oak Ridge National Laboratory,1999): 28.

6. Computed based on World Motor Vehicle Data 1996.

7. UN Centre for Human Settlements, An UrbanizingWorld (New York: United Nations, 1996); and WorldResources Institute, et al., World Resources Report 1996-97(New York: Oxford University Press, 1996).

8. UN Centre for Human Settlements, An UrbanizingWorld.

9. World Resources Institute, World Resources Report 1996-97.

10. Ibid.

11. Ibid.

12. Ibid.

13. U. S. Environmental Protection Agency, National AirQuality and Emissions Trends Report, 1997 (Washington,DC: U.S. Environmental Protection Agency, 1998).

14. UN Center for Human Settlements, An UrbanizingWorld.

15. World Resources Report 1996-97.

16. Ibid.

17. UN Development Programme, “UN Conference onEnvironment and Development Agenda 21: SustainableHuman Settlements Development” (New York: UNDevelopment Programme, 1992): chapters 7 and 9.

18.World Resources Institute,World Resources Report 1996-97: Box 14.3.

19. Joby Warrick, “160 Nations Endorse Pact on GlobalWarming Compliance,” The Washington Post, Nov. 15,1998, sec A: p.6.

20. UN Centre on Human Settlements, “UN Conferenceon Human Settlements (Habitat Conference) —IstanbulDeclaration on Human Settlements” (Istanbul: UN Centreon Human Settlements, 1996): paragraph 4.

21. Ibid.

Aphichat Chamratrithirong, et al., “The Study ofPopulation-Consumption-Environment Links: The Case ofAir Pollution in Bangkok” (Bangkok: Mahidol University,1998).

Mary Debus, Handbook for Excellence in Focus GroupResearch, prepared by Porter Novelli for the Academy forEducational Development (Washington, DC: Academy forEducational Development, 1991).

Edmund Egan et al., “Population-Consumption-Environment Links: Air Pollution and Transport Use in theWashington, D.C., Region” (Washington, DC: ICF KaiserInternational, Inc., 1998).

24

R E F E R E N C E S

A D D I T I O N A L R E F E R E N C E S

J. Leitman, “Energy Environmental Linkages in the UrbanSector” (Washington, DC: Urban ManagementProgramme, UN Centre on Human Settlements/UNDevelopment Programme/The World Bank, 1991).

José Luis Lezama, et al., “Population-Consumption-Environment Links: Air Pollution and Transport in MexicoCity” (Mexico City: Center for Demographic and UrbanStudies, El Colegio de México, 1987).

Wolfgang Lutz, Population, Development, Environment:Understanding Their Interactions in Mauritius (Berlin:Springer Verlag, 1994).

James J. MacKenzie, “Driving the Road to SustainableGround Transportation,” in Frontiers of Sustainability, eds.Roger Dower, et al.(Washington, DC: Island Press,1997):121-190.

Gayl D. Ness with Meghan Golay, Population and Strategiesfor Sustainable Development, a publication of The WorldConservation Union and UN Population Fund (London:Earthscan Press, 1997).

Population Reference Bureau, 1999 World Population DataSheet (Washington, DC: Population Reference Bureau,1999).

Paul C. Stern et al., Environmentally SignificantConsumption—Research Directions (Washington, DC:National Academy Press, 1997).

United Nations, World Urbanization Prospects, 1996Revision (New York: United Nations, 1998).

———————, Urban and Rural Areas 1996 (Wallchart)(New York: United Nations, 1997).

UN Centre for Human Settlements, “Implementation ofAgenda 21,” Report of the Executive Director (Nairobi,Kenya: UN Centre for Human Settlements, 1996).

25

——————————————, “The Management ofNatural Resources in the Context of Human Settlements,”Report of the Executive Director (Nairobi: UN Centre forHuman Settlements, 1996).

UN Environment Programme/World Health Organization,Urban Air Pollution in Megacities of the World (Oxford,England: Blackwell Publishers Ltd, 1992).

UN Population Fund, “Cairo 1994, World Programme ofAction of the International Conference on Population andDevelopment” (New York: UN Population Fund, 1994).

———————, “Environment for People: BridgingBridges for Sustainable Development” Papers presented atthe Special Session of the UN General Assembly on theUN Conference on Environment and Development FiveYears After (New York: UN Population Fund, 1997).

U.S. Census Bureau, Statistical Abstract of the United States1998 (Washington, DC: U.S. Department of Commerce,1998).

U.S. Environmental Protection Agency, National AirQuality and Emissions Trends Report, 1997 (Washington,DC: U.S. Environmental Protection Agency, 1998).

World Bank, 1999 World Development Indicators(Washington, DC: The World Bank, 1999)

Christopher Zegras, The World Bank’s Sustainable Transport:Priorities for Policy Reform and Its Relevance for UrbanTransport in Developing Countries (Washington, DC:International Institute for Energy Conservation, October1996).

THAILAND

INSTITUTE FOR POPULATION

AND SOCIAL RESEARCH,Mahidol UniversityAphichat ChamratrithirongPramote PrasartkulSureeporn PunpuingWathinee BoonchalaksiThirapong Santiphop

MEXICO

CENTER FOR DEMOGRAPHIC

AND URBAN DEVELOPMENT

STUDIES, El Colegio de MéxicoJosé Luis LezamaSilvia Luna SantosFortino Vela Peón Adriana Oropeza Lliteras

UNITED STATES

ICF KAISER

INTERNATIONAL, INC.Edmund EganPeter BonnerAmy ClemonsJonathan Cohen

POPULATION REFERENCE

BUREAU

Roger-Mark De Souza Alene GelbardKimberly CrewsRhonda SmithKaren Semkow

A P P E N D I X 2 :NOTES ON METHODOLOGY

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A P P E N D I X 1 :COUNTRY TEAMS

QUANTITATIVE:

Statistical Analysis

Research teams ran aseries of multiple regres-sions to determine statisti-cally significant relation-ships among householdstructure, consumption,and environmental impacts.To accomplish this, theteams calculated pollutioncoefficients using informa-tion on different pollution

emissions types, totalhousehold expenditures ongasoline and public trans-port, total householdincome, and householdsize. Based on the differentpollution coefficients, theteams then constructeddependent variables (mea-sures of transportationexpenditures) and selected aset of household socioeco-nomic variables as indepen-dent variables. Theseincluded household size,

percentage of householdmembers in certain age cat-egories (those under age 2,those under age 18, andthose over age 64), years ofeducation of the head ofhousehold, and after-taxhousehold income. Finally,the teams employed differ-ent regression models toexamine the net effect ofeach variable and regressionequation as a whole on thedependent variables.

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Sources of Data

ThailandFor Thailand, two

sources of data were used.The first was the HouseholdSocioeconomic Survey, 1994,conducted by the NationalStatistical Office. The sur-vey is conducted every twoyears. It is a nationally andregionally representativesurvey. The second was theReport on Thailand’sPollution Situation by theDepartment of ToxicControl, Ministry ofSciences, Technology andEnvironment. Data on theamount of air pollutionemission by mode of trans-portation measured in tonsper year were taken fromthe second source of data.

MexicoThe Mexican analysis

was based on a combina-tion of two sources of data:the National Income andExpenditure Survey (NIES) and the EmissionsInventory, both for 1994.The NIES is nationally rep-resentative with a total of

12,815 respondents andalso represents theMetropolitan Area ofMexico City (MAMC),with 1,738 cases. The sam-ple selected for the NIESwas weighted to produceestimates for the entirepopulation. The weightingprocedure entailed multi-plying each case by a statis-tical factor that was includ-ed in the same survey.Thus, the research teamwas able to obtain directmeasures for MAMChousehold expenditure ongasoline and public trans-portation as well as for a setof selected sociodemo-graphic variables such ashousehold income, house-hold size, head of house-hold’s schooling, head ofhousehold’s gender, andprivate cars per household.It was also possible to relatethe NIES MAMC house-hold data to the pollutantemissions data for theentire area of Mexico City.Pollutant emissions datawere obtained from theEmissions Inventory for1994, included in theProgram for Air QualityImprovement in the Valley of

Mexico, 1995-2000. Thisprogram has official datameasured in terms of tonsper year. In its analysis, theteam used only data onparticulate matter, carbonmonoxide, hydrocarbon,and total emissions associ-ated with both private andpublic transportation.

United StatesThe primary source of

data on consumer expendi-tures in the United Stateswas the 1995 ConsumerExpenditures Survey (CES),published by the Bureau ofLabor Statistics (BLS). TheBLS releases surveyresponses to questions suchas wages and income,demographic and house-hold information, andamount expended on dif-ferent types of commodi-ties. The CES also includesnational averages for differ-ent commodities, whichwere used to construct theemission coefficients. TheU.S. EnvironmentalProtection Agency (EPA) isthe major source of infor-mation on particulate emis-

sions. EPA’s 1995 NationalAir Pollutant EmissionTrends contains emissionsfor the six criteria pollu-tants for different on-roadtransportation sources,including light-duty gasvehicles (automobiles),motorcycles, and heavy-duty diesel vehicles (includ-ing buses). Additional datawere needed to disaggregatethe expenditure data onmotor fuel into automobileand motorcycle categories,and to disaggregate theheavy-duty diesel emissionsinto buses and trucks. Data for these estimates werederived from the Bureau of Transportation Statistics’1997 National Transpor-tation Statistics series.

QUALITATIVE:

Focus GroupInterviews

Focus group interviewssupplemented the quantita-tive data and providedinsights into the dynamics

of household transportationuse among various demo-graphic and income groupsin each country. The inter-views examined currentconsumption levels, con-sumer aspirations, and per-ceptions of the link amonghousehold size, consump-tion patterns, and environ-mental problems. Focusgroup participants weredrawn from important sub-groups of the national pop-ulations—urban elites,urban working class, andthe urban poor. The partic-ipants were selected and thegroups organized by ageand income levels. In thecase of the United States,the participants were alsoscreened to ensure racialand ethnic diversity. TheMexican and Thai researchteams also conducted in-depth interviews with poli-cymakers and city authori-ties to ascertain their atti-tudes and perceptions ofthe urban air pollutionproblem.

THE STUDY OFPOPULATION-CONSUMPTION-ENVIRONMENT LINKS:

The Case of AirPollution in Bangkok

INSTITUTE FOR POPULATION

AND SOCIAL RESEARCH,Mahidol UniversityAphichat ChamratrithirongPramote PrasartkulSureeporn PunpuingWathinee BoonchalaksiThirapong Santiphop

BackgroundThe level of air pollu-

tion in Bangkok frequentlyexceeds national air-qualitystandards, particularly forsuspended particulate mat-ter. This is largely the resultof activities in the trans-port, industry, and powersectors. In addition, severecongestion and the particu-lar mix of vehicle types inBangkok accelerate vehicu-lar air pollution. The aver-age traffic speed inBangkok is about 10 kilo-meters per hour, resultingin a notable amount of

unnecessary emissions. Inthe Bangkok MetropolitanRegion, vehicles contributefrom 60 percent to 70 per-cent of air pollution, whileindustry and domesticsources contribute the rest.

Because most ofBangkok’s workers live inthe periphery, there is agreat demand for commut-ing. Today, small, numer-ous households—thatinclude few children, ahigh proportion of house-hold members in the laborforce, and slightly moremembers who are elderly—increase transportationdemand. Private transportalready accounts for 51 per-cent of all daily trips, thehighest in any Asian city.The high growth rates ofprivate-vehicle ownershipmay be decreasing, howev-er, given the region’s recenteconomic downturn.

Findings From theQuantitative Analysis

The quantitative analy-sis showed strong linksbetween household charac-teristics and contributionto air pollution.

■ Male-headed householdsemitted about 2.7 kilo-grams more suspended par-ticulate matter (SPM) peryear than female-headed households.

■ Households whose heads worked in the salesand service and productionsectors produced about 3.7and 4.6 kilograms less SPMper year than householdsheaded by professionals orthose with administrative occupations.

■ Each increase of 1,000baht (about U.S. $26 atcurrent rates) in monthlyincome caused an increasein emissions of 0.1 kilo-gram per year.

■ Extended- and nuclear-family households producedapproximately 5.3 and 3.5kilograms more SPM peryear, respectively, than didone-person households.

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A P P E N D I X 3 :CASE STUDY SUMMARIES*

*Please see the inside of the backcover for information on how toorder individual case studies.

29

Findings From theQualitative Analysis

Following is a summa-ry of the findings from thequalitative analysis:

■ Bangkok inhabitantsregarded various healthproblems caused by air pol-lution as major concerns.All participants clearly feltthat air pollution was hav-ing adverse effects on theirhealth and that this mightbe affecting their quality of life.

■ People at all income levels of society recognizedthe impact of the individualon air pollution. Yet thisrecognition did not seem to affect commuting choices. While high- andmedium-income familiesuse their cars or motorcy-cles, the majority of thelow-income populationused the government’s masstransit system or privatecompanies’ bus services.The last group also rode

their own motorcycles orused the hired ones (motor-cycle taxis). Regardless ofincome level, families senttheir children to the mostprestigious schools possible.Because these schools werelocated in the city center,and because of safety con-cerns, parents reported dri-ving or accompanying theirchildren to school often.

■ Individualism and con-sumerism were seen todelay the development ofcommunity participation.Many focus group partici-pants felt that Bangkok’scivil society organizationswere not yet workingtogether in community-driven strategic planning to tackle issues that affectedpeople’s lives, such assprawl. Participants in-dicated that a lack of socialization and a lack ofempowerment made it diffi-cult for citizens to reassessdevelopment objectives andto collectively define long-term quality-of-life issues.

■ For Bangkok’s inhabi-tants, poor public trans-portation, work-relatedneeds, and convenience led to a reliance on the private car.

■ A lack of coordination of transportation policy wasseen to hinder implementa-tion of recommendations.Focus group participantsperceived that the formula-tion of a comprehensivetransportation policy hadlong been delayed becauseof the absence of anyauthoritative organizationwith clear responsibility forthe coordination of varioustransportation projects.Focus group participantsalso perceived a lack ofpolitical interest manifestedin a lack of accountability,transparency, honesty, andcoordination across differentdepartments.

POPULATION-CONSUMPTION-ENVIRONMENT LINKS:

Air Pollution andTransport Use inMexico City

CENTER FOR DEMOGRAPHIC

AND URBAN DEVELOPMENT

STUDIES, El Colegio de MéxicoJosé Luis LezamaSilvia Luna SantosFortino Vela Peón Adriana Oropeza Lliteras

BackgroundAir-quality problems in

Mexico City are created bya combination of social andnatural factors, such as thetechnology used to controlemissions in the transport,industrial, and service sec-tors; rapid populationgrowth with inadequateinfrastructure; and MexicoCity’s high altitude, whichresults in inefficient fuelcombustion. According tothe 1994 emissions inven-tory for the MetropolitanArea of Mexico City, morethan 4 million tons of pol-lutants are discharged intothe atmosphere yearly.SPM represents 11.3 per-

cent of the total amount of these pollutants.

The most importantcause of air pollution inMexico City is the urbantransport system. Vehicleemissions account for 75percent of the total amountof pollutants expelled intothe atmosphere. Private carsalone emit over half thisamount. Data for 1991show that, although privatecars accounted for only 15percent of all the journeysper person per day thattook place in Mexico City,they consumed 67 percentof all the energy used,emitting 5 to 6 more gramsof pollutants per journeyper day than petrol-fueledpublic transport and the highest amount of pollutants in the transportsector.

Nearly 45 percent of the 3 million cars inMexico City are over 10years old. At presentaround 36 million tripstake place in Mexico City,21.4 percent of which aremade by private cars. The transport system has

a very low average speed(36 kilometers per hour),which leads to greater emis-sions and more pollution.

Findings From theQuantitative Analysis

There are three generalfindings from the quantita-tive analysis:

■ Higher education andincome levels increased thehousehold’s contribution toair pollution. A high corre-lation was found betweeneducation and income, sug-gesting that those house-holds were in a better finan-cial position to afford pri-vate transport, and thatthey contributed more toair pollution.

■ Female-headed house-holds’ expenditure on pub-lic transportation had agreater impact on air pollu-tion. This might beexplained by the greater useof this kind of transporta-tion among female-headedhouseholds, where car own-ership is less common thanin male-headed households.There was, however, amajor impact on pollution

per capita in male-headedhouseholds, regardless ofthe kind of transportationused by members. This isbecause most households inMexico City are headed bymales.

■ Larger households spentmore money on transporta-tion, but households thatused a private car generateda greater share of pollution.The impact on pollutionwas great among house-holds that used publictransport (65 percent ofhouseholds accounting for30 percent of total atmos-pheric pollution), a findingexplained by the fact thatlarger household sizes wereinvolved. Households thatowned at least one car—35percent of all households inthe metropolitan area ofMexico City—contributed35 percent of householdpollution.

Findings From theQualitative Analysis

The following findingsare based on focus groupdiscussions:

■ Mexico City inhabitantsperceived various healthproblems due to air pollu-tion, but did not regardthese as a major concern.Despite the recognition of agrowing impact on health,participants seemed willingto live with air pollution.Low-income individualsseemed to be adaptingthemselves to the situationsimposed by the air pollu-tion risks. Medium- andhigh-income groups saw airpollution as a nuisancebecause it imposed addi-tional tasks, such as theinspection of car engines,and triggered driving bans(under the Hoy no circulaprogram) that limited theuse of cars to once—or incase of emergency twice—a week.

■ The perception of per-sonal impact on air pollu-tion varied according toincome level. Low-incomegroup participants for themost part used publictransport. They did not view themselves as

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A P P E N D I X 3 :CASE STUDY SUMMARIES c o n t i n u e d

31

contributing to air pollu-tion in using this mode oftransport and perceived pri-vate cars to be a majorcause of air pollution inMexico City. Medium- andhigh-income participantsrecognized that using theircars did contribute to theair pollution problem, butthey did not see it as amajor contributor.

POPULATION-CONSUMPTION-ENVIRONMENT LINKS:

Air Pollution andTransport Use in theWashington, D.C.,Region

ICF KAISER

INTERNATIONAL, INC.Edmund EganPeter BonnerAmy ClemonsJonathan Cohen

BackgroundSince the 1970s,

Washington, D.C., hasbeen one of the fastestgrowing metropolitan areasin the United States. Theregion has a rapidly diversi-

fying, post-industrial, ser-vice-based economy, and anincreasingly decentralizedpattern of urbanization.Growth in the District ofColumbia proper has notbeen nearly as large or asrapid as growth in theregion as a whole. Suburbshave seen the bulk of thenew growth, both in popu-lation and employment.This pattern has hadimportant implications fora transportation system thatwas designed to carry work-ers within the city, or fromsuburban houses to down-town jobs. People increas-ingly live in the suburbsand work in the suburbs,and for most people, thesesuburbs are not the sameones; cross-suburb com-muting is a major cause oftraffic congestion andextended commuting, andconsequently air pollution,in the region. It is notmerely growth but the loca-tion and type of growththat are partially responsi-ble for the air-quality prob-lem in the region.

Washington, D.C., alsosuffers from high, albeit

declining, concentrations of ground-level ozone, amajor source of urban airpollution. Ground-levelozone is produced by thecombination of nitrousoxides and volatile organiccompounds in the presenceof sunlight. Transportationis the leading source ofvolatile organic compoundemissions in the area, andthe second leading sourceof nitrous oxide emissions.Automobile use, in termsof vehicle-miles traveled per year, has increasedfaster than population.Congestion, which resultsin more pollutant emissionsper trip, has increased aswell, despite the construc-tion of over 400 miles ofnew freeways in the regionsince 1982.

A significant factor inthe urban transportationtrends in Washington,D.C., is the growing afflu-ent population attracted bythe growing number ofhigh-paying jobs in theregion. This translates intoincreasing expenditures onautomobiles and privatetransportation. In a highlydispersed, low-density set-

tlement pattern, automo-biles are increasingly indis-pensable for access to workand leisure activities. Thus,every household must havean automobile or risk beingsocially marginalized. If thehousehold has two workers,the standard in most of thecountry, then having twoautomobiles becomesincreasingly important.

Findings From theQuantitative Analysis

Household variablesaffected decisions on themode of transportationused. On average, two-par-ent households tended tospend the greatest amounton private (automobile)transportation, while one-parent households tendedto spend the most on pub-lic transportation. Elderlyhouseholds with higherincomes showed a distinctpreference for private asopposed to public trans-portation, perhaps becauseof personal safety concernsor because of the greaterconvenience of automo-

biles. Generally, highereducation, income, andhousehold size increasedtransportation demands.

More households reliedon private than on publictransportation. On average,two-parent householdstended to spend more onmore-polluting privatetransportation than did theother types of households,and their average totaltransportation expenditureswere higher as well.Although elderly house-holds spent less than otherson total transportation,their expenditures were alsoheavily biased toward pri-vate transportation. One-parent or one-adult house-holds, on the other hand,tended to divide theirexpenditures more equallybetween the two modes.The desire to drive an auto-mobile appears to beembedded in the culture ofmany Americans and wasreflected in the focusgroups. Changing the cul-ture of driving presents agreat challenge that, in the

absence of a major crisis,will require a long educa-tion process.

Findings From theQualitative Analysis

A review of the inputacross the focus groupsrevealed the followingopinions and ideas:

■ Air quality was seen ascontributing to quality oflife. Most participantseither directly identified airquality as a quality-of-lifeissue or established a causalrelationship between airpollution and illness.

■ Individuals did not feelas if they had control overtheir means of transport.Most participants believedthey needed to drive theirown cars, especially forwork or shopping. Theydid not think public trans-portation was sufficientlywidespread, available attimes they needed it, orsafe enough to provide acredible option.

■ Individuals did not feelthey had control over theirimpact on air pollution.

Most thought the impact ofone person changing his orher behavior would have aminimal impact on pollu-tion. Some groups believedthat collective action by cit-izens could have an impactin the local area or in theirparticular counties.

■ Most individuals accept-ed some responsibility fortheir choices impacting airpollution. People from allincome levels admitted thatindividuals were responsiblefor the level of air pollutionin the Washington area andthat their choices caused airpollution. Most immediate-ly identified the automobileas a major cause of air pol-lution and their own deci-sions to drive as a con-tributing factor. However,few took steps to reducethe amount of air pollutionby choosing not to drive orchanging their behavior inother ways.

■ Individuals believedthere was little public infor-mation connecting air pol-lution and health. Only

one group—older, low-income residents—made aclear connection betweenair pollution and healthrisk or disease and felt airpollution had a dramaticimpact on quality of life.Others saw some ill effectsin their own experiences—allergy problems, breathingdifficulties—but felt thatthere was no clear connec-tion. Most participantsthought that, if air pollu-tion’s detrimental effects onhealth were proven, obvi-ous, and widespread, theywould be more willing tochange their behavior. Theynoted the effectiveness ofpublic information andeducation initiatives, incen-tives, and legal and socialpressures applied in anti-smoking and householdrecycling campaigns andrecommended using similartactics in the effort toreduce air pollution.

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A P P E N D I X 3 :CASE STUDY SUMMARIES c o n t i n u e d

O R D E R I N G I N F O R M A T I O NTo request additional copies of this report or copies of the

U.S. case study, please contact PRB (see address on back cover).The full text of this report is also available on PRB’s Web site atwww.prb.org. To request copies of the Thai and Mexican case studies, please contact the following:

ThailandDr. Sureeporn PunpuingINSTITUTE FOR POPULATION

AND SOCIAL RESEARCH

Mahidol UniversitySalaya PhutthamonthonNakhon Pathom 73170Thailand

Tel.: 66-2-441-9666Fax: 66-2-441-9333E-mail: prspu@mahidol. ac.th

MexicoDr. José Luis LezamaCENTER FOR DEMOGRAPHIC

AND URBAN DEVELOPMENT

STUDIES

El Colegio de México, A.C.Camino al Ajusco No. 20Col. Peoregal Sta. TeresaCodigo Postal 01000 México, D.F.

Tel.: 525-645-1583Fax: 525-645-0464 E-mail: jlezama@colmex. mx

POPULATION REFERENCE BUREAU1875 Connecticut Avenue, NW, Suite 520Washington, DC 20009 U.S.A.

Tel.: (202) 483-1100Fax: (202) 328-3937E-mail: popref@prb.orgWeb site: www.prb.org