The leading cause of on-duty firefighter deaths is cardiac events triggered by overexertion and stress, accounting for roughly 59 to 65 percent of fatalities in any given year. But when you zoom out to include long-term occupational causes, cancer is now the single biggest killer of firefighters. In 2025, nearly 80 percent of firefighters honored at the International Association of Fire Fighters’ Fallen Fire Fighter Memorial died of occupational cancer. These two answers reflect different ways of counting, and both matter.
Cardiac Events on the Fireground
Heart attacks, sudden cardiac arrest, and other cardiovascular events have dominated on-duty death statistics for decades. In 2024, the National Fire Protection Association reported 40 fatal injuries from overexertion or strain, making up 65 percent of the 62 on-duty deaths it tracked. The U.S. Fire Administration’s count for the same year was slightly higher at 73 total deaths, with stress and overexertion responsible for 43 of them (about 59 percent). The numbers vary depending on how each agency defines “on duty,” but the pattern is consistent year after year.
What makes firefighting so dangerous for the heart is the combination of stressors hitting at once. When an alarm sounds, the body launches into a fight-or-flight response that raises the risk of a cardiovascular event five to seven times above baseline. Within minutes, a firefighter may be climbing stairs in full gear weighing more than 55 pounds, forcing open doors, dragging charged hose lines, or pulling victims from a burning structure. That gear is encapsulating and traps heat, driving up core temperature and accelerating dehydration. The physical demands blend heavy aerobic effort with bursts of anaerobic power and sustained static exertion, all while breathing heated, toxic air.
The firefighters who die this way almost always have some form of underlying cardiovascular disease, often undiagnosed. The strain doesn’t create heart disease from scratch. It overwhelms a system that was already compromised. When the cardiovascular load exceeds what a vulnerable heart can handle, it triggers arrhythmias, heart attacks, or sudden cardiac arrest. This is why national standards require medical screenings that look specifically for coronary artery disease, cardiac enlargement, uncontrolled high blood pressure, and other conditions that would make fireground work especially risky. Firefighters who can’t demonstrate a functional exercise capacity above a certain threshold are flagged for further evaluation.
Cancer: The Long-Term Killer
On-duty death statistics capture firefighters who collapse at a scene or on the way to one. They don’t capture the firefighter who retires at 55 and dies of bladder cancer at 62 because of decades of exposure to burning synthetic materials. When fire service organizations track all line-of-duty deaths, including those caused by occupational disease, cancer dominates the picture. Of the 311 IAFF members honored in 2025, 247 died of occupational cancer. That’s 79.4 percent.
Every fire produces a cocktail of carcinogens. Modern buildings burn hotter and release more toxic compounds than older wood-frame structures because they contain plastics, foam insulation, treated fabrics, and engineered materials. Firefighters absorb these compounds through the skin, through contaminated gear, and through inhalation even after the fire is out during overhaul operations. The cancers most associated with firefighting include cancers of the bladder, kidney, lung, brain, and digestive system, along with blood cancers like leukemia and non-Hodgkin lymphoma.
The gap between on-duty cardiac deaths and long-term cancer deaths explains why you’ll see different “leading cause” claims depending on the source. Both are accurate within their frame. If you’re asking what kills firefighters at the scene, it’s the heart. If you’re asking what kills the most firefighters overall, it’s cancer.
Traumatic Injuries and Vehicle Crashes
Traumatic injuries are the second most common cause of on-duty death, responsible for about a third of fatalities. In 2024, 18 firefighters died from trauma, accounting for 32 percent of deaths tracked by the NFPA. These deaths include structural collapses, falls, being caught or trapped in a burning building, and being struck by objects or vehicles at roadside incidents.
Vehicle crashes deserve special attention. Among volunteer firefighters, motor vehicle collisions are the second leading cause of death after cardiac events. A CDC analysis of firefighter deaths from 1994 through 2004 found that 26 percent of volunteer firefighter fatalities involved vehicle-related trauma, with 73 percent of those caused by collisions during emergency response. Seatbelt non-compliance remains a persistent problem. Federal evaluations have found that enforcing seatbelt use at all times the vehicle is in motion, along with better driver training and compliance monitoring, could meaningfully reduce these deaths.
Volunteer vs. Career Firefighters
The risks break down differently depending on whether a firefighter is volunteer or career. Volunteers account for a disproportionate share of on-duty deaths. During the 1994 to 2004 period analyzed by the CDC, 53 percent of all on-duty firefighter fatalities were volunteers despite the fact that not all emergency responses involve volunteers. Half of volunteer deaths were heart attacks, and a quarter were vehicle crashes during emergency response.
Career firefighters face different patterns. Heart attacks still lead at 39 percent, but asphyxiation accounts for 20 percent of deaths, largely from being caught or trapped inside burning structures. Career firefighters are more likely to be inside a building during active fire suppression, which increases their exposure to structural collapse and oxygen-depleted environments. For both groups, nearly all cardiac deaths (97 to 98 percent) were attributed to stress and overexertion rather than pre-existing symptoms that appeared before the emergency call.
Suicide and Behavioral Health
More firefighters die by suicide each year than from on-duty incidents, according to the U.S. Fire Administration. The Firefighter Behavioral Health Alliance tracks these deaths and believes the actual numbers are even higher because many go unreported. Firefighters face repeated exposure to traumatic scenes, sleep disruption from shift work, and a culture that has historically discouraged seeking mental health support. These suicides aren’t counted in traditional line-of-duty death statistics, which means they’re invisible in the data most people see when asking about firefighter fatalities.
Why the Numbers Stay High
Cardiac risk in firefighting is difficult to eliminate because the job itself is the trigger. You can screen firefighters medically, improve fitness programs, and identify those with hidden heart disease, but you can’t remove the physical demands or the adrenaline surge of an alarm response. Departments that adopt aggressive cardiovascular screening, annual fitness testing, and post-incident rehabilitation protocols see better outcomes, but many smaller and volunteer departments lack the resources to implement them consistently.
Cancer prevention has gained traction in recent years. “Clean cab” initiatives keep contaminated gear out of the crew compartment. Decontamination protocols call for washing gear and showering immediately after a fire. Some departments have switched to hoods and gear designed to block more particulate absorption through the skin. But these changes are unevenly adopted, and the firefighters dying of cancer today were exposed years or decades ago, long before any of these practices existed. The full impact of current prevention efforts won’t be visible for another generation.