Exercise in Polluted Air Hard on Heart, Report Says

People who exercise in highly polluted air may be risking heart attacks, according to the most extensive test of the effects of carbon monoxide on humans, published Saturday in the Annals of Internal Medicine.

Although the research concentrated on men and women with histories of heart disease, it found that carbon monoxide emissions from cars and industrial sites are a potential risk for anyone who exercises outdoors.

“It would be prudent to avoid exercise in areas that are polluted because it is just not healthy. And it’s possibly quite hazardous,” study director David Sheps, of the University of North Carolina in Chapel Hill, said in an interview.

In the study, 41 men and women who had histories of heart problems were subjected to cardiac, lung and blood tests while at rest and while riding a stationary bicycle. The volunteers then sat, idle, for several minutes in rooms with 100 and 200 parts per million carbon monoxide, after which they exercised and were tested again.

Volunteers exposed to carbon monoxide before or during exercise were three times more likely to suffer abnormal heartbeats or other cardiac irregularities associated with heart attack. Dangerous irregularities arose even when they sat still, breathing the carbon monoxide-rich air. Exercising or simply breathing in a carbon monoxide-rich environment also increased the rate of ischemia (blocked blood vessels) in all volunteers.