From the American Heart Association:
PALM HARBOR, Fla., March 13, 2009 —People who have had a heart attack are likely to report having been in traffic shortly before their symptoms began, researchers reported at the American Heart Association’s 49th Annual Conference on Cardiovascular Disease Epidemiology and Prevention.
In a German study of patients who had a heart attack, researchers found the patients to be more than three times as likely to have been in traffic within an hour of the onset of their heart attack. The researchers also observed small but statistically significant increases in the chance that a heart attack occurred within six hours after exposure to traffic.
Driving a car was the most common source of traffic exposure, but taking public transportation or riding a bicycle were other forms of exposure to traffic. Overall, time spent in any mode of transportation in traffic was associated with a 3.2 times higher risk than time spent away from this trigger. Females, elderly males, patients who were unemployed, and those with a history of angina were affected the most by traffic.