Fine Particulate Matter Air Pollution and Mortality in U.S. Cities

Jonathan Samet
Johns Hopkins--School of Hygiene and Public Health

Background: NIEHS supported research has been critical in establishing air quality standards aimed at protecting public health. This research and the regulations promulgated by the EPA in response, have led to great improvements in air quality. In 1987, the EPA added particulate matter less than or equal to 10 um (PM10) in diameter to the list of regulated pollutants. Despite improvements in air quality, epidemiologic studies have shown associations between PM10 concentrations well below the standard and number of deaths per day in several U.S. cities. In response to these findings, in 1987, the EPA promulgated new standards for particulate matter less than or equal to 2.5 um (PM2.5). Both the studies and the new standard have been criticized. A major issue is the cost of compliance with the standards for industry. Estimates to bring power plants, diesel trucks, and other sources into compliance range between $10 billion and $60 billion annually. However, the resulting health benefits are valued at $20-$100 billion per year.

Advance: These researchers assessed the effects of PM10, ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide on daily mortality rates in 20 of the largest cities in the U.S. The studies found consistent evidence that the level of PM10 is associated with increased rates of death from all causes and from cardiovascular and respiratory illnesses. The estimated increase in risk was 0.51% for each 10 ug/cubic meter increase in the PM10 level. This estimate is consistent with studies done by other researchers for other cities in the U.S. and other countries. There was weaker evidence that increases in ozone levels increased the risk of death in summer months. None of the other pollutants were significantly related to mortality rate.

Implication: This study adds to the body of data showing a correlation between increases in particulate matter and risk of death from all causes including cardiovascular and respiratory illnesses. These analyses provide evidence that particulate matter pollution continues to cause adverse health outcomes and strengthens the argument for maintaining air quality standards for this pollutant.

Citation: Samet JM, Dominici F, Curriero FC, Coursac I, and Zeger SL (2000). Fine Particulate Air Pollution and Mortality in 20 U.S. Cities. New England Journal of Medicine. 343 (24):1742-1749.