Exposure to Air Pollution May Lead to Cardiovascular DiseaseFeb 1, 2007
Researchers at the University of Washington report that long-term exposure to air pollution increases the risks of cardiovascular disease and death in postmenopausal women. The findings were published in today’s issue of the New England Journal of Medicine (NEJM).
The authors “studied 65,893 postmenopausal women without previous cardiovascular disease in 36 U.S. metropolitan areas from 1994 to 1998.” They concluded that “long-term (annual average) exposure to increased concentrations of fine particulate air pollution was associated with an increased risk of first cardiovascular events.” The increase in the risk of fatality was even higher. “The strongest overall association was with death definitely associated with coronary heart disease,” they report.
The UW study, sponsored in part by the Women's Health Initiative (WHI), was unique because it accounted for differing pollution levels within a particular city--rather than using average pollution levels for the entire metropolitan area. “In previous studies of the long-term effect of air pollution on cardiovascular disease,” they note, “investigators have averaged exposures across a city and then compared health effects between cities. However, gradients of exposure to pollutants within cities also affect the risk of death from cardiovascular causes…” Researchers measured air-pollution levels in the areas closest to each woman’s residence in order to get a more accurate assessment.
The study found that every increase of 10 micrograms per cubic meter in fine particulate air pollution was associated with a 24 percent increase in the risk of a cardiovascular event and a whopping 76 percent increase in the risk of death from cardiovascular disease. The same increase in pollution levels was associated with a 35 percent increase in the risk of cerebrovascular (blood vessels to the brain) events and an 83 percent increase in the risk of death from cerebrovascular causes.
The authors, led by Dr. Joel Kaufman of UW’s Environmental and Occupational Health Sciences department, conclude, “Our study provides evidence of the association between long-term exposure to air pollution and the incidence of cardiovascular disease. Our study confirms previous reports and indicates that the magnitude of health effects may be larger than previously recognized. These results suggest that efforts to limit long-term exposure to fine particulate pollution are warranted.”
In an NEJM editorial accompanying the report, Drs. Douglas W. Dockery and Peter H. Stone say that the study “greatly expands our understanding of how fine particulate pollution affects health…. The WHI study broadens the scope by finding that nonfatal cardiovascular events are also strongly associated with fine particulate concentrations in the community…. Perhaps most important, the WHI study established a stronger statistical association between fine particulate air pollution and death from coronary heart disease than [was] found in earlier studies.”
They also note that the “findings of the WHI study strongly support the recommendation for tighter standards for long-term fine particulate air pollution.”