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Air Pollution and Heart Health
The air we breathe can make us feel great or terrible--compare brisk mountain air to that of a smoggy city. The largest study of its kind shows that the quality of the air also has a larger than expected impact on heart health.
Dr. Joel Kaufman and colleagues at The University of Washington in Seattle, in the February 1, 2007 issue of the New England Journal of Medicine, published a large study showing that the incidence of heart disease increases with increased long-term exposure to air pollutants. The researchers followed nearly 66,000 postmenopausal women from 36 metropolitan areas without prior history of heart disease from 1994-1998. Exposure to air pollutants and incidence of first cardiovascular events were documented. Outcomes were adjusted for age, body mass, ethnicity, smoking, education, income, and the presence of chronic disease (high blood pressure, diabetes and high cholesterol).
The authors determined the effect of small particulate matter (PM2.5) on the occurrence of a first cardiovascular event, including coronary heart or cerebrovascular disease, heart attack, stroke, or coronary surgery. The average PM2.5 in this study was 13.5 units: ranging from 3.4 (Honolulu, HI) to 28.3 units (Riverside, CA). For each 10-unit increase, the risk of a cardiovascular event increased 24%, while the risk of death from cardiovascular disease increased a striking 76%. Similarly, the rate of cerebrovascular disease was increased by 35% and resulting deaths increased by 83% for the same increase in PM2.5 (Miller et al. 2007 N Engl J Med 356).
While smaller, short-term studies had established a possible connection between heart health and particulate air pollutants, this study provides strong evidence that the association is of greater magnitude than previously acknowledged. The fine particulate matter studied is commonly found in pollution caused by vehicle exhaust, industrial sources, and coal-burning. Heart health can now be added to the growing list of reasons to make efforts towards cleaning up the environment.
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