MONDAY, Nov. 10, 2003 (HealthDayNews) -- If you're unwise enough to smoke, you'd better keep a close eye on local air pollution levels, a French study indicates.
"We clearly showed that the heart attack rate was increased by 161 percent when the ambient air pollution index was high," says Dr. Yves Cottin, a professor of cardiology at the University Hospital of Dijon, who presented the findings Nov. 9 at the American Heart Association's annual conference in Orlando, Fla. "Smokers are particularly sensitive to air pollution, since we found a threefold increase risk in heart attack in the smoking population when the pollution is high."
The risk is closely associated with levels of fine particles, which mainly are generated by diesel engines, the study finds.
Cottin and his colleagues collected data on 322 Dijon area residents hospitalized for heart attacks in 2001 and 2002, looking at the relationship between incidence and levels of air pollution summarized in the ATMO index, which rates pollution on a scale of 1 to 10.
The pollution level rose to 6 or higher only 18 days of each year, but those days had the greatest incidence of heart attacks, especially for smokers, Cottin says.
Smokers "should reduce or stop cigarette smoking during poor air quality days," he says. "Smokers are also recommended to stay at home during those days."
And high pollution levels also call for special attention to the symptoms of a heart attack on high-pollution days, in case immediate emergency care is needed, Cottin says.
The French report is the latest addition to "a host of short-term and epidemiological studies that show an association between cardiovascular events and air pollution," says Dr. Robert D. Brook, an assistant professor of medicine at the University of Michigan and a member of an expert panel that is writing a position paper on the subject for the American Heart Association.
"Certain individuals are at especially high risk," Brook says. "They include smokers, the elderly, people with diabetes and children, in relation to asthma. This finding has been replicated all over the world, and an association has also been found with the risk of stroke."
Cottin says his group is studying the mechanism by which air pollution causes heart attacks and other cardiovascular problems. There is evidence that pollutants can contribute to an inflammatory process that leads to rupture of fatty deposits called plaques, releasing clots that block blood vessels, he says.
Some newspapers publish information on local air pollution levels on a regular basis, Brook says. Air pollution readings for communities across the country also are available daily on the Web site of the U.S. Environmental Protection Agency.