Study Links Traffic to Heart Attacks

October 21, 2004
You've suspected it and now a study in the New England Journal of Medicine confirms it: Sitting in heavy, urban traffic increases your risk of a heart attack. Perhaps a little more surprising -- bicyclists share the risk.

The study, conducted by the GSF-National Research Centre for Environment and Health in Neuherberg, Germany, says even being in traffic as a passenger in a car or bus increases the risk of a heart attack within an hour of your trip. The longer you're in traffic, the study says, the greater the risk.

"An association between exposure to vehicular traffic in urban areas and the exacerbation of cardiovascular disease has been suggested in previous studies. This study was designed to assess whether exposure to traffic can trigger myocardial infarction," the researchers said.

The study was conducted in southern Germany from February 1999 to July 2001. There were 691 subjects for whom the date and time of the heart attack were known, and who had survived for at least 24 hours after the event. They completed the registry's standardized interview, and provided information on factors that may have triggered the myocardial infarction. Data on subjects' activities during the four days preceding the onset of symptoms were collected with the use of patient diaries.

The research team concluded that people who spent the longest in traffic had the highest risk of heart attack, including cyclists, motorcyclists and bus passengers.

Seventy-two percent were in cars when in traffic. Eight percent had been in traffic just before their heart attack.

The highest risks were women and all people over 60, within an hour of being exposed to traffic.

As you might expect, the research shows the peak time traffic-induced heart attacks was the morning rush hour.