Heat exposure leaves firefighters at risk of heart attack

4 April 2017        

Category: Research

A person clasping their hands over their heart

Researchers that we've funded have shown that exposure to extreme heat whilst firefighting increases blood clotting and risk of heart attack. 

The study from researchers at the University of Edinburgh, and published today in the journal Circulation, may explain why cardiovascular events - such as heart attacks - are the leading cause of death amongst on-duty firefighters.

What does this mean for firefighters?

As a result, the researchers are now calling on fire services to help to reduce the number of firefighters suffering from heart attacks by limiting the time each individual spends tackling a blaze, as well as helping them to cool down and rehydrate after exposure.

A mock rescue

Nineteen non-smoking, healthy firefighters were randomly selected from the Scottish Fire and Rescue Service to participate in two exercises at least a week apart, including a fire simulation and a control exposure. The fire simulation exposed seventeen of the participants to extremely high temperatures, resulting in an average increase in core body temperature of 1 degree Celsius amongst participants as they attempted a mock rescue from a two-story structure.

66 per cent more likely to clot

The researchers used sophisticated techniques to measure blood vessel function and blood clotting and discovered that firefighters’ blood vessels failed to relax in response to medication. Their blood also became stickier and was over 66 per cent more likely to form potentially harmful clots after the fire simulation.

The research team believe that this increase in clotting was caused by a combination of fluid losses in sweat and an inflammatory response to the fire simulation, which resulted in the blood becoming more concentrated and thus more likely to clot. The researchers also showed that exposure to fire simulation causes minor injury to the heart muscle in healthy firefighters.

What could this mean for me?

The study’s findings are not directly applicable to the public; however, the combination of heavy physical exertion, high ambient temperatures and air pollution can present an increased risk in everyday life. As such, the researchers recommend that anyone who is exercising in high ambient temperatures should take regular breaks, keep well hydrated and allow time to cool down afterwards.

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