This is the main environmental cause of heart attacks

People have long believed that there was a link between air pollution and an increased risk of heart attack. But a new study shows that link is negligible. Instead, there is strong evidence that the main environmental factor in heart attacks is low temperatures. Here's what this means for you.

This weekend at the European Society of Cardiology meeting, Belgian medical researcher Marc Claeys presented the results of a massive study of environmental causes of heart attacks in 16,000 people in Belgium between 2006 and 2009. Claeys found no relationship between increased air pollution and increased numbers of heart attacks.

What he did find was that more heart attacks occurred in winter, when temperatures drop. But the connection continued beyond winter, too. He said "smaller differences in temperature between indoor and outdoor can also precipitate [acute myocardial infarction (AMI), or heart attacks]." An environmental cause is something that comes from outside the individual — so this study does not suggest that cold is a bigger factor than lifestyle issues like lack of exercise and high-fat diets.

There are a couple of possible reasons that lower temperatures could trigger a heart attack. Claeys suggested that lowered temperatures could stimulate cold receptors in the skin, which activate the sympathetic nervous system. This in turn releases adrenaline and related chemicals that are associated with heart attacks. Another possibility is that when the cold makes our blood slightly more thick and viscous, that leads to a greater risk of blood clots.

So what can you do? Claeys said:

Low temperature is by far the most important environmental trigger for AMI, whereas air pollution has a negligible effect. People at risk of AMI (for example elderly patients with diabetes and hypertension) can minimise their risk by avoiding big changes in temperature. This means wearing suitable clothes when going from the warm indoors to the colder outdoors, even beyond winter time.

So bundle up before you go out in winter, and avoid dropping your body temperatures quickly. Those simple activities could save your life.

Read more about Claeys' study on the European Association of Cardiology website