NEUHERBERG, GERMANY. Strenuous exercise, snow shoveling, anger and the use of cocaine or marijuana have all been linked with the acute risk of having a heart attack (myocardial infarction). Smoking, unemployment and conditions such as diabetes, hypertension and angina increase the vulnerability to heart attack, but are not considered acute triggers. Researchers at the German National Research Center for Environment and Health now add exposure to traffic as another acute risk factor. Their study involved 691 heart attack patients who survived for 28 days or longer. Interviews after their attack conducted by specially trained nurse researchers revealed that the risk of experiencing a heart attack was increased by a factor of 2 to 4 in the first hour following exposure to traffic; this, after correcting for other known acute risk factors such as severe exertion, being outside (air pollution), and getting up in the morning.
The risk increase applied to all common forms of transportation including driving a car, using public
transportation, bicycling and driving a motorcycle. The odds that a woman would have a heart attack was
4.5 times higher in the first hour following traffic exposure than at any other time. The corresponding odds
ratio for a man was 2.59. Having had a cold in the week before the attack also increased the risk, as did an
age over 60 years, and being exposed to traffic in the morning. Bicycling, perhaps because it combines
both traffic exposure and vigorous exercise, was associated with the highest risk (odds ratio of 3.94) of
experiencing a heart attack within an hour of finishing the ride. The researchers believe that exposure to
stress, noise and, in particular, traffic-related air pollution, are behind the observed increase in the risk of
having a heart attack after traffic exposure.