Air Pollution Is a Major Trigger of Heart Attacks, Study Finds
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Air pollution sets off nearly as many heart attacks as physical exertion, alcohol or coffee, a new review has found.

Air pollution accounts for 4.8 percent of heart attacks, while coffee and alcohol each accounts for 5 percent and physical exertion accounts for 6.2 percent, based on an analysis of data from 36 studies worldwide.

The results show that air pollution can harm not only the lungs, but the heart , said Dr. Andrea Baccarelli, an associate professor of public health at Harvard School of Public Health in Boston, who wrote an editorial accompanying the study online today (Feb. 23) in the journal Lancet.

"It is just a moderate risk factor, but because everyone is exposed to air pollution, it becomes very important on the community level," Baccarelli told MyHealthNewsDaily.

Heavy particles, inflammation and clotting are all hazards to the heart presented by air pollution, he said.

Common risks

Belgian researchers examined 36 studies conducted in various countries between January 1960 and January 2010 to examine the percentage of heart attacks attributable to common risk factors.

They took into account how much the general population is exposed to each risk factor. For example, cocaine use increases a person's heart attack risk by 23 times, but because so few people use the drug, it accounts for only 0.9 percent of heart attacks, according to the review.

They found that air pollution increased a person's heart attack risk by 5 percent. But because all the people in the studies were exposed to air pollution, its role in the risk for the general population is higher than some other factors, Baccarelli said.

The analysis also showed that drinking coffee increases a person's heart attack risk by 1.5 times, and drinking alcohol increases risk by three times, but more people are exposed to air pollution than drink coffee or alcohol.

Time spent in traffic or on the road accounted for 7.4 percent of heart attacks in the review, whereas negative emotions accounted for 3.9 percent and anger accounted for 3.1 percent, researchers said.

Heavy meals accounted for 2.7 percent, positive emotions accounted for 2.4 percent and sexual activity accounted for 2.2 percent of heart attacks, according to the review.

Adverse effects of air pollution

It's no surprise that air pollution has adverse effects on the heart, Baccarelli said. There are a number of ways heavy particles in the air, which come largely from traffic, and other pollutants can wind up affecting our bodies, he said.

Heavy particles from pollution can enter the lungs and bloodstream, allowing them to travel to the heart and increase heart disease risk, Baccarelli said.

Air pollutants also promote inflammation in the lungs, which can lead to inflammation of the heart and other parts of the body and can prompt a heart attack, he said. Inflammation of the lungs can also raise the risk of blood clots, which can damage the coronary arteries.

Pass it on: Air pollution accounts for about the same number of heart attacks as physical exertion, alcohol and coffee.

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