A European study shows that air pollution can worsen the health condition of people with heart disease when they exercise near heavy traffic.

A study by the University of Edinburgh and Umea University, published in Thursday’s New England Journal of Medicine, looked at the effect of diesel exhaust on a group of men with heart disease.

British cardiologist Nicholas Mills and colleagues at the University of Edinburgh and researchers in Sweden monitored 20 men who had had heart attacks at least 6 months prior to the experiment. All had been successfully treated and were in stable condition, Mills emphasized.

Each man was monitored closely to prevent any health problems. The men were exposed for one hour to diluted diesel exhaust as they exercised in an isolated chamber – the participants rode an exercise bike for two 15-minute periods and rested in between.

In other words, the experiment resembled the exposure a jogger or a cyclist would experience in heavy traffic.

The researchers found that the heart’s electrical activity decreased significantly. The exposure to pollution reduced an essential anti-clotting substance in the blood and worsened exercise-induced ischemia - insufficient flow of blood and oxygen to the heart. This can lead to a heart attack and even death.

Mills’ study is the first in which heart patients are directly exposed to pollution.

This is consistent with previous studies that showed long-term exposure to air pollution increases the risk of cardiovascular problems. In addition, it is a warning for people with a heart disease to avoid exercising in polluted air.

According to the American Heart Association, about 16 million Americans have heart disease. A large number of Americans also suffer from asthma, bronchitis and chronic obstructive pulmonary disease. They are advised to avoid polluted air when exercising.

The researchers also insisted that patients with heart and respiratory diseases should continue to exercise regularly, as it is beneficial to overall health. With the note that they avoid polluted areas.