Particulate Matter

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).