Exposure to traffic increases the risk of a heart attack

In a study conducted by Annette Peters, Ph.D., Hannelore Lowel, MD and their co-workers who were participating in the Cooperative Health Research in the Region of Augsburg Study Group and which was published in the New England Journal of Medicine, the authors found that exposure to traffic was a strong predictor of subsequent heart attack.

The researchers stated that an association between exposure to vehicular traffic in urban areas and the exacerbation of cardiovascular disease had been suggested in previous studies. This study was designed to assess whether exposure to traffic can trigger a heart attack.

The researchers conducted a case-crossover study in which cases of myocardial infarction were identified with the use of data from the Cooperative Health Research in the Region of Augsburg Myocardial Infarction Registry in Augsburg, in southern Germany, for the period from February 1999 to July 2001.

There were 691 subjects for whom the date and time of their myocardial infarction were known, who had survived for at least 24 hours after the event, and who provided information on factors that may have triggered their heart attack. Data on subjects' activities during the four days preceding the heart attack were collected with the use of patient diaries.

A highly significant association was found between exposure to traffic and the onset of a myocardial infarction within one hour afterward (odds ratio, 2.92; 95 percent confidence interval, 2.22 to 3.83; P<0.001).

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 a heart attack. Adjusting for the level of exercise on a bicycle or for getting up in the morning changed the estimated effect of exposure to traffic only slightly (odds ratio for myocardial infarction, 2.73; 95 percent confidence interval, 2.06 to 3.61; P<0.001).

The subject's use of a car was the most common source of exposure to traffic; nevertheless, there was also an association between time spent on public transportation and the onset of a myocardial infarction one hour later.

The authors concluded that even a brief exposure to traffic may increase the risk of myocardial infarction in susceptible persons.

Air pollution - specifically exposure to traffic fumes - is a potent cocktail of oxidants, placing your body under servere oxidative stress and consequential free radical attack.

Source: New England Journal of Medicine. 2004 Oct 21;351(17):1721-30.