Keep-fit types who jog or cycle in polluted cities are actually increasing their chances of developing heart failure, according to a new study.
The research suggests that built-up cities like London could prove highly dangerous for those taking part in vigorous exercise as lungs will be forced to work harder, narrowing blood vessels as a result.
This in turn would put an extra strain on the heart, increasing the risk of cardiac arrest.
Experts from Brussels University Hospital concluded that exercising in clean air is just as important to reducing the risk of heart disease as cutting cholesterol from our diet.
The study, that was carried out on 16,295 people, saw subjects exposed to diluted diesel exhaust fumes over a two-hour period before they were given a cardiac stress test.
Researchers found that those exposed to the fumes suffered a harmful effect when the heart was stimulated during exercise.
Lead author Dr Jean-Francois Argacha said: “This suggests that pollution is more harmful to the lung circulation during exercise.”
He added: “This is a major public health issue for people living in polluted urban areas where exercise could damage the lungs and potentially lead to decompensated heart failure…
“Our main advice is to limit physical activities during heavy air pollution.”
Top pic: Rex