Can't 'anticipate when you'll be in a burning building'

A study of healthy, non-smoking firefighters shows that exposure to extreme heat and physical exertion increases blood clotting and the risk of a heart attack.

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

Syd McNully is a firefighter who tells Today he had a heart attack while working aged just 36.