While only women were studied, researchers believe that air pollution has the same effects on men. However, women are at greater risk for heart disease in general, because their arteries are narrower and thus more easily blocked.
Researchers in the Women's Health Initiative Observational Study studied more than 65,000 women between the ages of 50 and 79 in 36 different U.S. cities for nine years. At the beginning of the study, none of the women had heart disease. At the end of the study, researchers compared the frequency of heart disease among participants in the different cities with information on local air quality. They found a substantial correlation between the density of particulate matter in the air and the occurrence of cardiovascular disease.
"These soot particles ... are typically created by fossil-fuel combustion in vehicles and power plants, " said lead researcher Joel Kaufman of the University of Washington. "The tiny particles — and the air pollutant gases that travel along with them — cause harmful effects once they are breathed in."
The average particulate levels varied by city, from four to nearly 20 micrograms per cubic meter of air. A 10 microgram increase in particulate concentration corresponded to a 76 percent greater chance of a woman dying from cardiovascular causes, including heart attacks and strokes.
"This adds to the mounting evidence that air pollution should be taken seriously as a risk factor for cardiovascular disease," said Jeremy Pearson, associate medical director for the British Heart Foundation.
The study's authors also urged stricter standards on particulate emissions.
According to Pearson, the British Heart Foundation is funding research on how to minimize the harm from air pollution. "In the meantime," he said, "when localized air pollution is particularly high, people with ... coronary heart disease should avoid staying outside for long periods."