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Health Effects Institute: Particulate Matter Research Program

Health Effects Institute, Boston, MA

About HEI. The Health Effects Institute (HEI) is an independent, nonprofit corporation chartered in 1980 to provide high-quality, impartial, and relevant science for decision makers on the health effects of air pollutants from motor vehicles and other sources. The Institute is supported jointly by the US Environmental Protection Agency (EPA) and industry. HEI has funded over 200 studies and published over 150 Research Reports on the health effects of pollutants, including carbon monoxide, air toxics, nitrogen oxides, diesel exhaust, ozone, and particulate matter (PM). HEI also periodically produces Special Reports reviewing topics such as the health effects of diesel exhaust and oxygenates in fuel.

HEI’s PM Research Program. Understanding the health effects of PM is an important part of HEI’s research. Although many epidemiologic studies conducted in different locations have found associations between short-term increases in ambient PM concentrations and increases in hospital admissions and deaths in people with pre-existing cardiopulmonary diseases, many questions remain about the strength of these associations and their “plausibility”, that is whether these associations can be explained in terms of pathophysiologic changes. The major questions that HEI has addressed over the last 5 years are:

  1. How strong is PM epidemiology?
  2. How can assessment of exposure to PM be improved?
  3. What are plausible mechanisms by which PM causes adverse health effects and what popula-
    tions are susceptible?
  4. Which particle components are most toxic?

HEI has made substantial progress in all these interrelated areas. PM epidemiology has been enhanced through a reanalysis of two large studies of the long-term effects of PM, a major time-series study of the association between daily mortality and PM in 90 cities across the US with different patterns and levels of air pollution (NMMAPS), and the application of new and revised statistical approaches.

Other HEI studies have contributed to exposure assessment by assessing whether measurements taken at monitoring sites are correlated with personal exposure measurements, and by evaluating the contribution of indoor and outdoor sources to personal exposure.

Finally, HEI has funded several epidemiologic studies and controlled inhalation exposure studies in human volunteers and animals measuring a variety of health endpoints. Together with research by others, this work has shown possible initial changes in mechanistic pathways, such as inflammatory responses in the airways and changes in cardiac and vascular parameters. Studies using laboratory-generated PM of different composition and size have suggested that both particle size and composition may be important determinants of effects.

Overall, the HEI PM program in the last five years has published 31 Research Reports, three Special Reports on PM epidemiology, and two HEI Perspectives reviewing PM epidemiologic and experimental evidence with a focus on HEI studies, and made multiple contributions to key EPA and other decision documents.

Among many activities, a major future effort will be a systematic approach, through toxicology and epidemiology research, to investigate whether some components or sources of PM pose greater health concerns than others. Additional information about HEI and its research program can be found at the HEI web site www.healtheffects.org exit EPA.

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