Heat exposure puts firefighters at risk of heart attacks

Firefighters physical exertion was found to be a factor. Picture: John Devlin
Firefighters physical exertion was found to be a factor. Picture: John Devlin

Exposure to heat and the physical exertion required to control a blaze is putting firefighters at risk of heart attack, research suggests.

A study funded by the British Heart Foundation (BHF) found that tackling fires puts a strain on the heart, increases blood clotting and worsens the function of blood vessels.

Sign up to our public interest bulletins - get the latest news on the Coronavirus

Previous work has shown firefighters have the highest risk of heart attack of all the emergency services.

A heart attack is the leading cause of death for on-duty firefighters and they tend to suffer cardiac arrests at a younger age than the general population. In the US, around 45 per cent of on-duty deaths each year among firefighters are due heart issues, with most heart attacks occurring as fires are put out.

In the new study, published in the journal Circulation, 19 non-smoking healthy firefighters - 16 of whom were men - from the Scottish Fire and Rescue Service took part in a standard training exercise. They attended on two occasions, at least one week apart, and either performed a mock rescue from a two-storey building for 20 minutes or undertook light duties, in the case of the control group, for 20 minutes.

The firefighters wore heart monitors that continuously assessed their heart rate and its electrical activity. Blood samples were also taken before and after, including measurement of a protein called troponin that is released from the heart muscle when it is damaged.

Those taking part in the rescue had core body temperatures that rose by 1C and stayed that way for three or four hours.

There was also some weight loss among this group, while their blood vessels also failed to relax in response to medication. Their blood became “stickier” and was more than 66 per cent more likely to form harmful clots than the blood of people in the control group. Researchers from the University of Edinburgh said the results showed “striking changes in physiological measures of cardiovascular function”. They said: “Participation in fire simulation training places an inordinate strain on the cardiovascular system.”

The researchers said they believed the increase in clotting was caused by a combination of fluid loss in sweat and an inflammatory response to the fire simulation, which resulted in the blood becoming more concentrated and likely to clot.