First Responder Fitness: The Firefighter Cardiac Numbers

In 2025, 81 firefighters died on duty in the United States. Forty-eight of them died from cardiovascular events. Those figures are provisional, published by the U.S. Fire Administration pending its full 2025 report, but the shape of them is not new. It has been the shape of this job for thirty years.

Fire is not the leading cause of death in the fire service. The heart is.

The number that has not moved

The USFA states that sudden cardiac events "kill more firefighters on duty than any other cause and are responsible for about 45% of firefighter line-of-duty deaths," based on its fatality reports covering 2018 through 2022. In the same document it notes cardiovascular events account for "about eight times more than deaths due to asphyxiation."

Go back further and the figure barely shifts. A NIOSH alert on preventing firefighter cardiovascular fatalities reported that for the ten-year period 1995–2004, "44% (440/1006) of on-duty fire fighter fatalities" were due to sudden cardiac death.

Forty-four percent across 1995–2004. About forty-five percent across 2018–2022. Three decades of improved turnout gear, better SCBA, better fireground tactics, and the cardiac share of line-of-duty deaths is effectively unchanged.

What killed firefighters in 2025

The USFA's provisional 2025 breakdown by cause:

Cause	Fatalities
Stress or overexertion	48
Vehicle collisions	13
Struck by object	6
Fall	4
Assault	3
Caught or trapped	2
Collapse	2
Out of air	1
Contact with	1
All others	7
Unknown	1

Source: U.S. Fire Administration, provisional 2025 data.

One line on that table is larger than every other line combined. Worth noting honestly: 48 of 81 is a higher share than the 45% long-run average, and because the 2025 data is provisional, it is not yet grounds for calling a trend. One year is one year.

The risk is not spread evenly across the shift

This is the part that gets lost. The cardiac risk in this job is not a flat background hum across a 24. It spikes hard, on specific tasks, and the spikes are enormous.

A CDC study of duty-related sudden cardiac death among firefighters aged 45 and under examined 205 age-eligible on-duty sudden cardiac deaths recorded by the USFA between 1996 and 2012. Compared with non-emergency duties:

Duty	Relative risk of sudden cardiac death	95% CI
Fire suppression	22.1×	14.8–32.9
Physical training	4.8×	3.2–7.2
Alarm return	4.1×	2.7–6.2
Alarm response	2.6×	1.5–4.6
EMS and other non-fire emergencies	0.5×	0.3–1.0

Source: CDC / NIOSH.

Estimates of the fire-suppression multiplier vary a great deal depending on method and population, and it would be dishonest to present one as settled. The NIOSH alert cites a case-control analysis putting the odds ratio for fire suppression at 64.1 (95% CI 7.4–556) — note how wide that interval is — with training at 7.6 and alarm response at 5.6. The USFA, citing later work, states the risk "is 10-100 times higher during fire suppression compared to nonemergency duties."

Twenty-two times, sixty-four times, somewhere between ten and a hundred times. The researchers disagree on the magnitude. None of them disagree on the direction.

Two further details from that CDC dataset are worth sitting with. Physical training carried a relative risk of 4.8 — the training meant to protect firefighters is itself one of the higher-risk windows. And "all 16 SCDs associated with alarm response occurred among volunteer firefighters," a signal about who is going from rest to full exertion with no warm-up and, often, no recent medical evaluation.

The clock runs differently here

The NIOSH alert notes that "over 75% of the deaths occurred while traveling to or from an incident, at an incident, or during training activities," and that the majority of on-duty cardiovascular fatalities happened in the afternoon or evening.

That last point is a genuine anomaly. NIOSH describes it as "in stark contrast to the circadian rhythm of coronary heart disease deaths in the general population, in which the majority of these deaths have been found to occur in the early morning hours." The general population dies of heart disease at dawn. Firefighters die in the afternoon and evening — when the call volume is.

The job is writing the schedule.

The deaths are the visible part

The NIOSH alert also records that in 2005, "an estimated 765 fire fighters suffered an on-duty cardiovascular event that did not result in sudden death."

The USFA puts it plainly: fatal sudden cardiac events "may just be the tip of the iceberg." For every line-of-duty death counted, there is a much larger population of firefighters who had an on-duty cardiac event, survived it, and are somewhere in the system — on light duty, in rehab, medically retired, or back on the truck.

What the fire service says to do about it

NIOSH reviewed its own fatality investigations and ranked the recommendations it issued most often. For medical fatalities in both 1998–2005 and 2006–2014, the top two categories were the same: medical screening first, fitness and wellness second, with medical clearance for duty third in the later period. Across 2006–2014 there were 742 firefighter line-of-duty deaths; NIOSH initiated 282 investigations and completed 279 of them.

On the standards side, the 2024 U.S. Fire Administrator's Summit health and wellness workgroup reported that recent Tentative Interim Amendment changes to NFPA 1582 "now base cardiorespiratory fitness guidelines on age and sex-based norms for all firefighters (candidates and incumbents)," and that "if a firefighter falls below the established percentile, they are placed on restricted duty," with the standard then requiring "an individualized assessment plan by a physician." The same report states the IAFC position that "every fire chief should adopt and implement a comprehensive health and fitness program, including annual medical evaluations and cancer screenings that meet NFPA 1582."

And then the workgroup says the uncomfortable thing out loud: "Ironically, most occupational medical evaluations do not screen for these underlying conditions, but rather simply assess risk factors." Its conclusion is that evaluations "must adopt more sensitive testing to more effectively identify occult coronary vessel disease in fire/EMS personnel." Read that as written. The screening many departments run is checking boxes that correlate with heart disease rather than looking for heart disease.

What to take from this

Nothing here is a protocol, and nothing here is medical advice. It is the published record of what the leading cause of death in this profession actually is, where in a shift it strikes, and what the fire service's own bodies say should be done about it.

Three things stand up on their own. The cardiac share of on-duty deaths has not improved in thirty years, while almost every other category of firefighter death has. The risk is concentrated in identifiable windows — fire suppression above all, but also physical training and the return from an alarm. And the annual medical that a lot of firefighters treat as an administrative nuisance is, according to NIOSH's own review of its own fatality investigations, the single most frequently issued recommendation after a firefighter dies of a medical event.

If your department runs NFPA 1582 medicals, take them seriously. If it does not, that is worth raising with your chief, and the IAFC has already said the same thing in writing.

By Brian M. Parks · Founder, Combat Nutra

This article reports published federal and fire-service data for general information. It is not medical advice, and it is not a claim about any product. Direct questions about your own cardiovascular health to a qualified clinician.

The Leading Cause of On-Duty Firefighter Death Isn't Fire