Particulate Matter

Perspectives 1 is the first of a series produced by the HEI Health Review Committee to integrate findings across several HEI studies or entire research programs. The intent is to describe and interpret results bearing on important and timely issues for a broad audience in terested in environmental health.

Dr Checkoway and colleagues at the University of Washington tested the primary hypothesis that increases in daily fine particle levels were related to increased risk of out-of-hospital sudden cardiac arrest. Sudden cardiac arrest and questionnaire data, and exposure data were obtained from the Puget Sound Clean Air Agency (Seattle WA). The investigators used a case-crossover study design; for each case of sudden cardiac arrest, a time period when the person was disease free was selected as a matched "referent" period.

Dr. Mark Goldberg and his colleagues at McGill University conducted a time-series study in Montreal using available data from the Quebec Health Insurance Plan and mortality and air pollution data to better the understanding of the mortality-particulate association. Because of the comprehensive nature of this health insurance database, the investigators were able to link individual deaths in Montreal to medical information up to 5 years before death.

A Special Report of the Institute's Particle Epidemiology Reanalysis Project. The overall objective of this project was to conduct a rigorous and independent assessment of the findings of the Harvard Six Cities and American Cancer Society Studies of air pollution and mortality. This objective was met in two parts. In Part I: Replication and Validation, the Reanalysis Team led by Dr. Daniel Krewski sought to replicate the original studies via a quality assurance audit of a sample of the original data and to validate the original numeric results.

In an effort to address the uncertainties regarding the association between PM and daily mortality, and to determine the effects of other pollutants on this association, HEI funded the National Morbidity, Mortality, and Air Pollution Study (NMMAPS). Dr Jonathan Samet and his colleagues at Johns Hopkins University, in collaboration with investigators at Harvard University, conducted this time-series study in large cities across the US where levels of PM and gaseous pollutants were varied.

Dr John Godleski and colleagues at Harvard School of Public Health conducted an exploratory study to test the effects of particulate matter exposure in dogs, which share many features of the human cardiovascular system. The investigators hypothesized that particulate matter might affect the animals' cardiac function, leading to arrhythmia, and might induce inflammatory responses and changes in pulmonary mechanical measurements. Twelve dogs were exposed to concentrated ambient particles (CAPs) that were 30 times their level in ambient Boston air.

Drs. Douglas Dockery at the Harvard School of Public Health and C. Arden Pope III at Brigham Young University speculated that exposure to PM might lead to a transient drop in blood oxygenation, which might have serious consequences in humans with heart or lung problems. The investigators designed a study to increase the possibility of observing PM effects by testing a potentially at-risk group (the elderly) at a time of year that historically had experienced relatively high levels of PM (the winter).

Communication 5 contains proceedings of a workshop held in Cambridge, MA, December 3–4 1996. Presentations included: Current Understanding of the Health Effects of Particles and the Characteristics That Determine Dose or Effect; Particle Formation in Combustion; The EPA Particle Emissions Testing Procedure; Characterizing Particulate Matter in Motor Vehicle Exhaust; Atmospheric Aerosol Transformation; Generating Particles for Laboratory Studies; and Issues and Research Needs for Particle Characterization.

The Phase I.A Report of the Particle Epidemiology Evaluation Project. The Health Effects Institute began the Particle Epidemiology Evaluation Project in 1994 to evaluate the emerging epidemiologic evidence of a relation between particulate air pollution and daily mortality. In Phase I.A, Drs. Jonathan M. Samet and Scott L. Zeger and their colleagues at the Johns Hopkins University School of Hygiene and Public Health (1) reconstructed from original sources the data set for Philadelphia used in earlier studies and confirmed previous numerical results from analyzing these data; (2) developed an analytic approach (including new statistical methods) based on the Philadelphia data set; and (3) applied this approach to data sets for six locations: Philadelphia; Utah Valley; St. Louis, MO; Eastern Tennessee; Birmingham, AL; and Santa Clara County, CA.

HEI conducted the Environmental Epidemiology Planning Project in order to identify research needs and opportunities in selected areas of environmental epidemiology. Working groups in each selected area prepared documents composed of individually authored papers. The Planning Project documents were originally published in Environmental Health Perspectives (December 1993, Vol. 102).