Heart attack cases are not all the same, but we need to understand why firefighters are more prone to having a heart attack related to their daily activities at work than a normal person. In the article “Emergency duties and heart disease deaths among firefighters in the United States” Stefanos N. Kales writes “A heart attack occurs when the blood supply to a segment of the heart muscle is extremely reduced or interrupted . This happens when one of the corridors that supply blood to the heart muscle is obstructed by a blockage. This blockage can be due to a condition called atherosclerosis (a buildup of fatty substance along the mass of the course), a clotting of the blood, or a coronary vessel adapting to an overall blockage. In the event that the blood supply to a part of the heart is interrupted, that part of the heart will no longer receive the oxygen or supplements necessary to complete its capacity and will be destroyed. If a small part of the heart is included, it will be able to function without it.” “One study shows that heart attacks accounted for 45% of firefighter deaths” (Kales). For firefighters, inhaling smoke and other dangerous hydrocarbons often leads to this “fatty” blockage of the heart vessels. The lack of sleep that firefighters also experience a