Women living in areas with higher levels of air pollution have a greater risk of developing cardiovascular disease and subsequently dying from cardiovascular causes.
This University of Washington study appearing in the Feb. 1 issue of The New England Journal of Medicine. The study is one of the largest of its kind, involving more than 65,000 Women’s Health Initiative Observational Study participants, age 50 to 79, living in 36 cities across the United States.
UW researchers studied women who did not initially have cardiovascular disease, following them for up to nine years to see who went on to have a heart attack, stroke, or coronary bypass surgery, or died from cardiovascular causes. They linked this health information with the average outdoor air pollution levels near each woman’s home, and found that higher pollution levels posed a significant hazard ? much higher than previously thought ? for development of cardiovascular disease.
The researchers studied levels of fine particulate matter, which are tiny airborne particles of soot or dust, and can come from a variety of sources, like vehicle exhaust, coal-fired power plants, industrial sources, and wood-burning fireplaces. These particles are less than 2.5 microns in diameter — about 30 to 40 of them would equal the diameter of a human hair. Particulate matter levels are monitored and regulated by the U.S. Environmental Protection Agency (EPA). They’re typically invisible to the human eye once they’re in the atmosphere, though they may be visible in dense clouds as they come out of a tailpipe, smokestack or chimney, and are responsible for urban haze.
“These soot particles, which are typically created by fossil-fuel combustion in vehicles and power plants, can contain a complex mix of chemicals,” explained Dr. Joel Kaufman, professor of environmental & occupational health sciences, epidemiology, and medicine at the UW, and leader of the study. “The tiny particles ? and the pollutant gases that travel along with them ? cause harmful effects once they are breathed in.”
They also found that local differences in particulate matter levels within a city, as well as exposure differences between cities, translate to a higher or lower risk of cardiovascular disease and related death.
“Our findings show that both what city a woman lived in, and where she lived in that city, affected her exposure level and her disease risk,” said Kristin Miller, first author of the study and a doctoral student in epidemiology at the UW.