Study Finds New Road Hazard: Heart Attacks

Finds that pollution, not stress, is the culprit

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HealthDay Reporter

WEDNESDAY, Oct. 20, 2004 (HealthDayNews) -- If you think being stressed while stuck in traffic can give you a heart attack, think again. A new study says you're more likely to suffer a coronary from the pollution caused by traffic.

"The time the subjects spent in cars, on public transportation, or on motorcycles or bicycles was consistently linked with an increase in the risk of myocardial infraction [heart attack]," said a report in the Oct. 21 issue of the New England Journal of Medicine.

The study was done in Germany but originated in the United States. Annette Peters, now an epidemiologist with the GSF-National Research Center for Environment and Health in Neuherberg, participated in several similar studies done at institutions related to Harvard Medical School, got funding from an American source and then did the German study.

Peters and her colleagues used information on 691 people who suffered heart attacks, collecting data on their activities in the four days that preceded the attack. They found that those who had been in traffic had three times the risk of having a heart attack within one hour afterward as those who had not been in traffic.

Although the journal report drew the cautious conclusion that "transient exposure to traffic may increase the risk of myocardial infarction in susceptible persons," Dr. Peter H. Stone, who wrote an accompanying editorial, said the evidence pointed clearly to air pollution as the villain, rather than other factors such as the stress of driving.

"The clever design of this particular study was to look not only at drivers, who have the most stress, but also at passengers in streetcars and bicycle riders," said Stone, who is director of the clinical trials center at Brigham and Women's Hospital in Boston. "Presumably the stress of driving would not be present at all, or would be less so, in individuals in buses or on bicycles. The effect of all of them was basically the same."

Stone's editorial describes in detail how pollutants -- especially fine particles produced by autos, buses and trucks -- can induce fatty plaques in an artery to rupture, causing a heart attack.

The results of Peters' new study are consistent with one done several years ago at the Harvard School of Public Health, when she was a postdoctoral student there, said Douglas Dockery, a professor of environmental epidemiology, who took part in the previous studies. That study found a link between driving and the risk of heart attack.

"This study is certainly consistent with the hypothesis that exposure to air pollution in traffic is associated with increased risk," Dockery said.

Work elsewhere points in the same direction, he said, citing a trial in which state troopers in North Carolina were fitted with heart monitors. Abnormal heartbeats were associated with exposure to air pollution during the troopers' workday, Dockery said.

Should a driver wear a face mask or take other protective measures? No, Stone said, because pollution is a societal issue.

"The import of this kind of information is not that as individuals we should change our behavior, but that we should have policy-makers improve air quality so that we would all be better off," he said.

More information

The scientific case for a link between air pollution and heart problems is laid out by the American Heart Association.

SOURCES: Peter H. Stone, M.D., director, clinical trials center, Brigham and Women's Hospital, Boston; Douglas Dockery, Sc.D., professor, environmental epidemiology, Harvard School of Public Health, Boston; Oct. 21, 2004, New England Journal of Medicine

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