Most people believe that a firefighter’s biggest on-the-job threat is fire or a collapsing building, but according to a recently released Harvard study, 45 percent of on-duty deaths of firefighters are from heart disease. A new study reported in the Journal of the American Heart Association (JAHA) this past week found heart disease common among firefighters who died of cardiac arrest. It has been no secret among firefighters that the silent killer of the community is cardiac events with n ...