Being exposed to traffic fumes increases your risk of heart attack by a third, according to a German study presented at this week’s American Heart Association meeting in Palm Harbor, Florida.

The study was made by Annette Peters, PhD, and colleagues at the Institute of Epidemiology, Helmholtz Center, Munich, Germany. They interviewed 1,454 people who survived heart attacks and found out that in many of the cases, one hour prior to their heart attacks, they had been caught in traffic jam.

The researchers found that women were in the higher-risk group together with elderly males, patients who were out of work and those with a history of angina. They were 3.2 times more likely to suffer a heart attack in the first hour after being in traffic.

The researchers did not give a specific reason for which people had had a heart attack, but speculated that “one potential factor could be the exhaust and air pollution coming from other cars. But we can’t exclude the synergy between stress and air pollution that could tip the scale,” Peters said.

Air pollution has always been thought to reduce survival due to its noxious effects on people’s health. Previous studies have linked pollution to increased risk of heart attack, stroke, lung cancer, asthma and other serious diseases.  

A study published in Thursday’s New England of Medicine shows that people who live in areas with the most ozone pollution are 25 percent to 30 percent more likely to die from lung disease than those living in areas with the cleanest air.

About 240,000 people in the United States and 7.7 million people worldwide die of respiratory disease each year, according to data from the World Health Organization.