The MESA

Air Pollution Study 

Strengthening the 

Scientific Foundation for Air 

Quality Management

While it is widely known that 

factors such as cigarette smoking 

and high blood pressure are 

linked to cardiovascular disease, 

studies indicate that long-term 

exposure to air pollution also is 

associated with premature death 

from this disease.

In 2004, the Environmental Protection Agency (EPA )

awarded a grant to the University of Washington for the Multi-Ethnic 

Study of Atherosclerosis (MESA) Air Pollution Study—an unprecedented investigation of the impact of air pollution on hardening 

of the arteries, or atherosclerosis. This long-term study investigates 

key questions about the possible effects of fine particles in 

air pollution on the development of heart disease and mortality.

www.epa.gov/ncer
Building Knowledge 

of PM Health Effects

In accordance with its mission to protect human health, 

the ultimate goal of EPA’s PM research program is to 

provide information for decision-making. EPA conducts 

and funds research designed to answer key questions 

concerning pollution emissions, exposure, health effects 

and air quality management.

EPA’s Science to Achieve Results (STAR) 

research program, through its competitive grants 

process, has funded several epidemiological studies 

investigating long-term exposure to PM2.5 in 

addition to the MESA Air Pollution Study. STAR 

support of the study will substantially add to this 

body of research.

Improving our Knowledge Base

The MESA Air Pollution Study investigates the impact 

of air pollution on the progression of cardiovascular 

disease among more than 7000 participants with diverse 

backgrounds from nine locations in six states for 10 

years. The central scientific hypothesis for this study is 

that long-term exposure to fine particles is associated 

with a more rapid progression of coronary atherosclerosis and an increased risk of coronary events.

To test this hypothesis, a host of air pollution and 

participant health measures are being collected and 

analyzed. Along with measuring PM concentrations 

and variability at the neighborhood, home and individual levels, the MESA Air Pollution Study is using 

data from the national PM2.5 monitoring system. These 

environmental data will be integrated into a model to 

estimate long-term PM exposure for all study participants. The cardiovascular health of each participant 

also will be tracked, with a subgroup of 3600 participating in additional medical evaluations for subclinical, asymptomatic progression of atherosclerosis.

The MESA Air Pollution Study will address 

the following critical scientific questions concerning 

PM-related health effects:

1. What role does long-term particle 

exposure play in the progression of coronary artery disease and the onset of clinical 

cardiovascular disease, including heart 

failure, heart attacks and mortality?

2. Are some ethnic populations more susceptible to the effects of particle exposure?

3. Does the presence of gaseous pollutants 

change the health risks associated with 

ambient particulate matter?

Collaborating with Preeminent 

Researchers: the MESA Study

The MESA Air Pollution Study is built on the framework of the Multi-Ethnic Study of Atherosclerosis 

(MESA) which is a 10-year, large-scale epidemiological 

study of cardiovascular risk factors and atherosclerosis 

initiated in 1999 by the National Heart, Lung, and 

Blood Institute (NHLBI) of the National Institutes of 

Health. NHLBI-MESA recruited at baseline approximately 1100 participants aged 45-84 years in each of six 

major metropolitan areas—Los Angeles, CA, St. Paul, 

MN, Chicago, IL, New York City, NY, Baltimore, MD, 

and Winston-Salem, NC. MESA researchers continue 

Air Pollution and Cardiovascular Health

E

missions from power plants, traffic, wood 

burning, and other combustion processes form 

airborne particles and liquid droplets of chemicals. While inhaled particulate matter (PM) ranges 

in size from particles tens of micrometers in diameter 

(PM10) to minute particles less than 0.1 micrometer in 

diameter, combustion sources generate fine particles 

less than 2.5 micrometers in diameter (PM2.5), just 

1/30 the width of a human hair.

Two landmark studies, originally published in the 1990s with later followup reports, indicated that these fine particles pose the greatest mortality risk 

from air pollution.1-4 In 1999 and 2006, EPA revised the National Ambient 

Air Quality Standards for particulate matter to address PM2.5 concentrations. 

Since 1999, EPA also has supported a national PM2.5 monitoring network, 

managed by federal, state and local governments.

Although scientific evidence is accumulating that supports the link between 

PM exposure and premature mortality and adverse health events, many questions about the health effects of PM remain unanswered. In 2001, the National 

Research Council highlighted a critical need for further research on the longterm health effects of PM exposure, particularly in two areas: the effects of PM 

in combination with gaseous pollutants (such as nitrogen dioxide and ozone), 

and the effects on potentially susceptible groups. The MESA Air Pollution 

Study addresses these and other research needs.

The MESA Air Pollution Study
Research Collaboration 

Encouraged 

The investigators of the MESA Air Pollution Study 

invite proposals from other investigators to explore 

additional research questions. Researchers can gain 

access to monitoring data or physiological data and 

samples from both the NHLBI-MESA and MESA Air 

Pollution Studies. The proposed research must secure 

independent funding. Further information about 

research opportunities and the process for proposing 

collaborative projects can be obtained at the MESA 

Air Pollution Study Web site or by contacting the 

principal investigator, Dr. Joel Kaufman. (Please see 

contact information on the back page.) 

Behind the MESA Air Pollution Study

The Multi-Ethnic Study of Atherosclerosis (MESA)—

the NHLBI epidemiological study—is the foundation 

of the MESA Air Pollution Study. The collaborating 

institutions in the NHLBI-MESA also are participating in the MESA Air Pollution Study. These 

collaborators include the University of CaliforniaLos Angeles, Columbia University, Northwestern 

University, University of Minnesota, Johns Hopkins 

University, Wake Forest University, University of 

Vermont, and Tufts-New England Medical Center. 

The University of Southern California and University 

of Michigan are also collaborators.

The MESA Air Pollution Study is based at 

the University of Washington Department of 

Environmental and Occupational Health Sciences. 

The study’s Principal Investigator is Dr. Joel 

Kaufman. The study’s exposure assessment efforts 

are directed by Dr. Martin Cohen.

Expected Outcomes

The MESA Air Pollution Study will provide:

• More precise estimates of the risks for the progression of 

underlying coronary artery disease and mortality associated 

with long-term exposure to ambient PM2.5.

• More information on the role played by traffic-related air 

pollution and regional air pollution. 

• Identification of groups especially susceptible to the effects 

of PM2.5 exposure due to racial/ethnic background, poor 

health status, older age, and other characteristics. 

• A better understanding of the health risks posed by exposure 

to gaseous pollutants concurrently with particulate matter. 

• Opportunities for research collaboration.

The MESA Air Pollution Study will help determine 

if cardiac disease is accelerated by exposure 

to PM in combination with gaseous pollutants.

www.epa.gov/ncer

MESA Air Pollution Study: In Brief

Study Population

• More than 7000 

participants 

recruited from 

the NHLBI-MESA 

Study, the NHLBIMESA Family 

Study, and additional participants 

in New York and 

southern California

Study Sites 

(Nine Locations)

• Six field sites established 

by the NHLBI-MESA 

Study in Chicago, Los 

Angeles County, Baltimore, 

St. Paul, New York City, 

and Winston-Salem 

• An additional area near 

New York City and two 

additional areas in and 

around Los Angeles

Study Approach

H e a lth As s es sm e nts :

• All participants tracked for clinical cardiovascular 

events (heart attack, heart failure, death, etc.)

• A subgroup of 3600 receive two clinical examinations 

five years apart to be assessed for pre-symptomatic 

progression of atherosclerosis

PM Expos u r e As s es sm e nts :

• Air pollution data collected from existing networks, 

study-specific outdoor monitors, roughly 330 

monitors in homes, and personal monitors (carried 

by approximately 80 participants)

• PM2.5 exposure model developed, based on air 

monitoring and questionnaire data
to conduct medical evaluations, including collecting 

detailed health data from participants who will receive 

a total of four clinical examinations by 2007.

Several academic institutions have secured grant 

funding to address additional scientific questions 

in the NHLBI-MESA study population, including 

measurements of lung function (MESA Lung Study) 

and genetic markers of susceptibility to disease 

(MESA Family Study). The University of Washington 

designed the MESA Air Pollution Study in partnership with the NHLBI-MESA researchers. The 

investigation of the role of PM in cardiovascular 

health relies on and adds to the NHLBI-MESA effort. 

The MESA Air Pollution Study is recruiting several 

hundred additional study participants and will repeat 

clinic health assessments in 2010 for the subgroup 

of 3600 participants undergoing further assessment 

for asymptomatic evidence of atherosclerosis. The 

supplemental data collection will contribute to the 

value of the broader NHLBI-MESA goals.

using soPhisticated 

exPosuRe assessMents

The MESA Air Pollution Study team will combine 

air quality data collected by government agencies 

with the study’s own monitoring effort to develop an 

exposure model. This model will combine air quality 

data, meteorological data, traffic information, land 

1 thE prOgrEssiOn and OnsEt Of hEart disEasE

in determining associations with PM 

exposure, the MESA Air Pollution 

Study is assessing heart disease at 

three levels: 

• The occurrence of cardiovascular events, such as 

heart failure, heart attack, 

stroke, angina, and medical 

interventions;

• Changes in asymptomatic 

cardiovascular disease; and, 

• Early indicators of biological 

stress.

At the study’s inception, participants were free of clinically-recognized (or symptomatic) cardiovascular 

disease. for the duration of the 

study, they are being followed for 

the occurrence of cardiovascular 

events and cardiovascular death. 

All participants provided data on 

individual characteristics, activities and behaviors, medical history 

and current use of medications, diet 

and dietary supplements, and social 

determinants of health. Every year 

the study participants are contacted 

to report medical diagnoses made 

by a physician, significant medical 

procedures, and to identify deaths 

that may have occurred. All reports of 

cardiovascular diagnosis and death 

are verified by study physicians using 

hospital medical records and death 

certificates.

A subgroup of 3600 participants 

is undergoing additional clinical 

assessment for the progression of 

cardiovascular disease in its early, 

symptom-free stages. To identify 

underlying heart disease, investigators are using the following advanced 

noninvasive medical techniques:

• Computed tomography (CT) 

scans to determine the presence of coronary artery calcification, a reliable indicator of 

atherosclerosis. 

• Ultrasounds to assess the 

thickness of the arterial wall at 

specific points on the carotid 

artery (in the neck). This 

measurement, referred to as 

intima-media thickness (IMT), is 

used to determine the extent of 

atherosclerosis and the risk of 

heart attacks and strokes.

strengthening the scientific foundation for air Quality Management

noninvasive tests will enable researchers to 

compare the progression of early, symptom-free 

heart disease with levels of PM exposure.

answering critical Questions PHoTo CREDIT: CATHy NUN

The study follows 

a diverse group of 

men and women from 

communities distributed throughout six 

metropolitan areas. 

St. Paul

Los Angeles

Chicago

Winston-Salem

Baltimore

New York 

 City

SOURCE: MESA AIR

PoLLUTIoN DATABASE

AUTHOR: MICHALIS AvRAAM

mesa air Pollution stu dy 

Field Centers

FEBRUARy 6, 2006
use and other geographic data, and individual time 

activity data to estimate the exposure levels of each 

study participant.

Recognizing that air pollution varies within metropolitan areas, investigators are characterizing exposure 

down to the neighborhood level. To supplement the 

fixed air quality monitors maintained by government 

agencies, study personnel have conducted monitoring 

in the communities and outside of about 100 homes in 

each study area. Within 18 months of joining the study, 

participants have had PM2.5 and gaseous pollutants 

measured two times for two-week periods using neighborhood monitors. To determine how much outdoor 

air pollution contributes to indoor PM exposure, some 

participants’ homes have been equipped with indoor 

monitors for these same two-week periods. Lastly, to 

get a more precise estimate of individual exposure and 

to verify the assumptions used in the project’s exposure model, some participants from these households 

are wearing personal monitors.

Outdoor monitors also will be used to identify 

relationships between PM concentrations and factors 

such as distance to major roads and other PM sources. 

These relationships will be incorporated into the 

exposure model in order to estimate exposure concentrations at each participant’s residential address.

The University of Washington has leveraged this 

monitoring effort with the support of the Health 

Effects Institute to study the role of PM components 

on health effects associations. 

To gain insight on how PM 

could induce atherosclerosis and 

heart disease, investigators also 

are assessing a subgroup of 720 

subjects for plasma (blood) markers 

of inflammation, oxidative damage, 

and impaired blood vessel function. Research has shown that these 

biological markers may play a role 

in the development and progression 

of atherosclerotic plaques in the 

blood vessel wall.

2 diffErEncEs in suscEptibility

The risk of coronary artery disease 

has been shown to vary by race 

and ethnicity. nHlbi-MESA and the 

MESA Air Pollution Study are 

following a diverse group of older 

men and women between ages 50-89. 

investigators will consider whether 

individual characteristics, such as age, 

the presence of subclinical disease 

or risk factors for diseases, residential location (inner-city or suburban), 

education level, and race or ethnicity, 

increase susceptibility to the adverse 

health effects of long-term exposure 

to ambient PM. They also will consider 

the influences of factors that result 

in a higher exposure burden, such 

as physical activity levels, differences 

in outdoor activities, residential proximity to pollution sources, housing 

characteristics, air conditioner 

use, and exposure to indoor particle 

sources, such as wood-burning 

stoves and cigarette smoke.

3 pm and gasEOus pOllutants

Depending on geographic location 

and season, ambient PM levels can 

be associated with certain gaseous 

co-pollutants. Health responses 

might be stimulated by a mixture 

of PM components or by the simultaneous or sequential exposure to 

gaseous pollutants, such as ozone, 

in ambient air. The comprehensive 

monitoring and modeling being done 

in the MESA Air Pollution Study will 

help researchers and policymakers 

better understand health effects 

from PM in combination with other 

ambient pollutants.

r aCe/etHn iCit y 

oF study PartiCiPants 

The MESA Air Pollution Study population 

is comprised of the following races and 

ethnicities: 38% white, 28% African-American, 

22% Hispanic, and 12% Asian (predominately 

of Chinese descent).

MESA Air Pollution Study researchers are conducting air monitoring 

at each study location to understand the variation in concentrations 

of selected pollutants within the communities where participants 

reside. The monitors on the lamppost in the first photo are two 

of more than 100 sited periodically throughout each study area 

measuring nO2 and nOx. These monitors are used to determine the 

spatial variability of air pollution levels and the contribution from 

vehicular traffic. The monitor in the second photo will remain in place 

for the duration of the study and is measuring trends over time in 

PM2.5, nO2 and nOx

Photo credit: Sure

 as well as the impact of nearby traffic.

Sh 

thur air atnam/maria Barne yPhoto credit: Sar a duBowSk y

 White

 AfricanAmerican

 Hispanic

 Asian

38%

28%

22%

12%
Office of Research 

and Development

Washington DC 20460 

EPA/600/S-06/003 

December 2006

Joel Kaufman, M.D., M.P.H. 

Principal Investigator

Dept. of Environmental and 

Occupational Health Sciences

School of Public Health 

and Community Medicine

University of Washington

Box 354695 

Seattle, Washington 98105-4695

(206) 897-1723

mesaair@u.washington.edu

Barbara Glenn, Ph.D. 

Physical Scientist

U.S. Environmental Protection Agency

Office of Research Development

National Center 

for Environmental Research

8723F

1200 Pennsylvania Avenue, N.W.

Washington, D.C. 20460

(202) 343-9721 

glenn.barbara@epa.gov

Recycled/Recyclable. Printed with vegetable oil based inks 

on 100% post-consumer process chlorine free recycled paper.

Contacts for the MESA Air Pollution Study

References 1 The Harvard Six-Cities Study:

Dockery, D.W., Pope, C.A. III, Xu, X., et 

al. (1993). An association between air 

pollution and mortality in six U.S. cities. 

N Engl J Med 329:1753-59.

2 Follow-up of the Harvard Six Cities 

Study: Laden, F., Schwartz, J., Speizer, 

F.E., Dockery, D.W. (2006). Reduction 

in fine particulate air pollution and 

mortality: extended. Am J Respir Crit 

Care Med 173:667-72.

3 American Cancer Society studies:

Pope, C.A. III, Thun, M., Namboodiri, M., 

et al. (1995). Particulate air pollution as 

a predictor of mortality in a prospective 

study of U.S. adults. Am J Respir Crit 

Care Med 151:669-74.

4 Pope, C.A. III, Burnett, R.T., 

Thurston, G.D., Thun, M.J., Calle, E.E., 

Krewski, D., Godleski, J.J. (2004).

Cardiovascular mortality and long-term 

exposure to particulate air pollution: 

epidemiological evidence of general 

pathophysiological pathways of disease. 

Circulation. 109(1):71-7.

Web Resources

The MESA Air Pollution Study 

www.mesaairpollution.org | This site provides study information, background, 

and contacts.

EPA National Center for Environmental Research (NCER) 

www.epa.gov/ncer | This site describes EPA’s extramural research program for 

exposure, effects, risk assessment, and risk management. NCER supports the 

STAR (Science to Achieve Results) grants program and graduate and undergraduate 

fellowships programs. Details regarding the MESA Air Pollution Study can by found 

by conducting a search for grant number R831697 at www.epa.gov/ncer/grants.

EPA Particulate Matter and Air Pollution 

www.epa.gov/air/particlepollution | EPA provides information on PM, including 

general description, health effects, environmental effects, regulatory actions, monitoring, and links to research.

AIRNow 

www.airnow.gov | This cross-agency Web site provides the daily Air Quality Index 

with maps and information on day-to-day air quality in the United States.

EPA Particulate Matter Research 

www.epa.gov/pmresearch | These pages describe the research being done by 

EPA to better understand particle emissions, transport and atmospheric chemistry, 

and particle exposure and associated health effects.

Disclaimer: The research described in this document has been funded partially by the 

U.S. Environmental Protection Agency under the STAR Program. The information does not 

necessarily reflect the views of the Agency, and no official endorsement should be inferred.