Firefighting - A Toxic Profession

Published in the 2013 October Syner​gist

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Today’s Fires A​re More Dangerous than Ever

By Dawn Bolstad-Johnson

On day one of fire training academy, firefighters learn that firefighting is a mentally taxing and toxic profession and that they are likely to die 10 years earlier than if they had chosen ​any other career. In the U.S., we lose about 100 firefighters to line-of-duty deaths each year, a statistic that is flat regardless of how many improvements are made to the system of personal protective equipment (PPE), or “turnout gear," used by firefighters. These line-of-duty deaths do not typically capture the cancer deaths that may be related to the countless toxic exposures that firefighters accumulate over their 20-plus years of service.

Some experts believe that the improvements to firefighter PPE are actually posing new hazards to firefighters because they allow firefighters to expose themselves to fires for longer periods. With the older equipment, career firefighters knew that they had to leave a fire when the tips of their ears started to burn—about 20 minutes in the heat-intensive fire environment. New equipment provides longer periods of thermal protection, which is pushing firefighters to use larger air bottles so they can work longer. 

But heat is not the only hazard that firefighters face. Turnout gear provides protection from heat, but not from chemical or particulate exposure. Fire conditions are full of nanoparticles, and the health hazards of nanoparticle exposure are not fully understood. Further, skin as a route of entry for toxic materials has not been well-reviewed, though it is the elephant in the room that no one’s talking about. And the hazards don’t end there.

Toxicity of Today’s H​omes

The contents of our homes have changed drastically over the years, and we’ve increased the level of toxicity in our homes exponentially. Fifteen years ago, we did not have flat-screen TVs, smartphones, computers, and so on. Building materials have changed as well; oriented strand board (OSB), particle board, and injected, expandable foams with chemical names that are difficult to pronounce are among the more modern materials.

Flame retardants, which are often injected into plastics, foams, and fabrics to protect items from catching fire, are another major contributing factor to this increased toxicity. Currently, no regulations limit the amount of decabromodiphenyl ether (deca-BDE), a popular brominated flame retardant, that can be injected into a material. Exposure to flame retardants is a concern not only for firefighters, but for the general public as well. This stuff is so prevalent that as plastic items decay, deca-BDE is released into our house dust, and we are eating it. There have also been reports that this material is found in the cord blood of newborn babies. Even so, it is not on the radar of regulators—let alone firefighters.

The modern materials in our homes have also increased the toxicity of today’s fires, and we don’t know how these acute exposures impact firefighters’ health. And modern materials aren’t the only concern; even structures built with legacy materials such as wood and cotton can create a toxic, carcinogenic environment during a fire.

In November 2009, Underwriters Laboratories, a global independent safety science company, conducted a side-by-side comparison of two simulated living room fires—a modern furnished room and a legacy furnished room—and filmed the resulting fires. The modern furnished room, which was filled with synthetic materials, burned to flashover—the condition in which the gases generated from the fire catch fire themselves—in less than four minutes from the time of ignition. In contrast, the legacy furnished room, complete with cotton-filled couches and a wood frame, did not reach flashover conditions for nearly 30 minutes. The video is available at 

If your home has modern synthetic furnishings and is filled with electronics, like many homes today, you may not have time to get out if there is a fire—and that’s due to the fire alone, not its toxicity. By the time the firefighters arrive, four to five minutes from the time of dispatch, they will be exposing themselves to the aftermath of a very toxic fire. 

Firefig​hters Love Fires

Just as surgeons like to perform surgery, firefighters love to fight fire. However, the majority of calls these days are for emergency medical services (EMS): heart attacks, car accidents, falls, and so on. An informal review of 911 calls revealed that the total fire-related call volume for a metropolitan EMS fire department may represent only 10 percent of all calls to a 911 dispatch center. That 10 percent included small fires such as food burning on the stove and car fires, as well as more challenging structure fires. Firefighters live for “good” fires, and since those only come along once in a long while, firefighters want to maximize their time fighting the blaze.

The self-contained breathing apparatus (SCBA) bottles that firefighters carry on their backs may allow them only 20 minutes of air. To maximize their time fighting fire, firefighters will wait to “click in” the regulator for their SCBAs until the moment they enter the door to a structure fire. This practice may buy them three to five additional minutes of firefighting time, but waiting to smell that first whiff of smoke means they are inhaling air full of carcinogens—many of which may be above ceiling values or in an as-low-as-reasonably-achievable (ALARA) category of exposure. While SCBA provides the best protection available, this human factor—firefighters’ cultural practice—compromises that level of respiratory protection.

Fire Overh​aul

The danger isn’t gone once the fire is put out: hazardous contaminants are present even after a fire is extinguished. In the after-fire environment, firefighters perform fire overhaul, the mop-up phase of firefighting, during which they look for hot embers and ensure that the fire won’t rekindle. 

About 15 years ago while working at the Phoenix Fire Department, I learned that firefighters were testing for the presence of carbon monoxide (CO) after a fire and using the level of CO as an indicator of when it was “safe” to remove their SCBA. In other words, they were operating under the impression that if CO was at a low acceptable level, then all other contaminants were low as well. 

It’s no secret that CO is usually the “killer gas” if a firefighter runs out of air. CO is a byproduct of incomplete combustion and is found in elevated levels at every fire, regardless of the contents burning. The hemoglobin in our bloodstream—the protein in red blood cells that carries oxygen—has a greater affinity for CO over oxygen by 240 times. Too much exposure to CO produces a condition of carboxyhemoglobin: instead of delivering oxygen to the cells in the body, the blood is delivering CO. This can lead to a condition of hypoxia, a shortage of oxygen in the body, followed by severe confusion, combativeness, and death from CO poisoning. 

Although CO is a huge threat during active firefighting conditions, once fires are extinguished, CO usually disappears fairly quickly. In my opinion, CO is not the biggest health threat during fire overhaul conditions. Although humans are able to detect some harmful contaminants—acid gases, for instance, provide great warning to avoid overexposure to hazardous contaminants because they affect mucous membranes—some of the major health hazards at fire scenes can’t be detected with your senses (for example, known carcinogens such as formaldehyde and toxic irritants such as glutaraldehyde and acrolein).

After learning of this CO monitoring practice, I asked a Phoenix Fire assistant chief how they determined that CO was the indicator gas for all other contaminants that may be present in an after-fire environment (also known as fire overhaul). In other words, how did they know it's safe for firefighters to remove their SCBAs if CO is low? His answer: “Well, I don’t know. That’s just the way we have always done it.” 

In 1998, with the support of the Phoenix Fire Department, I set out to identify contaminants of combustion present during fire overhaul. The study, which was published in the May 2000 issue of the AIHA Journal, involved sampling 26 independent live house and commercial fires. The data showed that CO does not predict the presence of anything but CO. There is no relationship between CO and the numerous hazardous contaminants we sampled, including polynuclear aromatic hydrocarbons (PNAs), benzene, toluene, ethyl benzene, xylene, hydrochloric acid, acetaldehyde, acrolein, benzaldehyde, formaldehyde, glutaraldehyde, isovaleraldehyde, nitrogen dioxide, sulfur dioxide, and hydrogen cyanide. Even now, 15 years later, firefighters’ behavior hasn’t changed much.

A Needed Cultural Change

Industrial hygienists are trained to look for exposures that may cause disease or injury, whereas firefighters are more concerned with hazards that may take their lives immediately—a collapsing wall or building, running out of air during an intense firefight, not being able to find their way out of a burning building. Firefighters should protect themselves from the moment they arrive on the fire scene. This includes clicking in their SCBA regulator before walking to the fire and not waiting until after they detect smoke and inhale their first whiff of toxic air.

As firefighters’ protective gear improves, along with the technology to predict some of the more obvious threats to life, the focus may shift to the silent toxic exposures that accumulate over the career of a firefighter. Today, firefighters who come on the job are each assigned an SCBA. This is already a cultural shift from 30 years ago, when firefighters were considered to be “wimps” if they used an SCBA at all. An SCBA used to be “the thing that stayed in the box on the truck.” 

Culture is slow to change, but as health and safety is increasingly promoted in the fire service as well as in the general population, there is now a heightened awareness about the causes of cancer, including chronic exposures such as those faced by firefighters. Young firefighters are healthy and strong and want to sustain their health into retirement. 

Still, education is the key. Firefighters need to know what they are exposed to and how to protect themselves as building materials and the contents inside our homes become more synthetic and less organic.  

Dawn Bolstad-Johnson, MPH, CIH, CSP, is director of Health, Safety, Environment and Quality at PHI Air Medical LLC in Phoenix, Ariz. She can be reached at (602) 224-3519 or 


 Suggested Readings


“Characterization of Firefighter Exposures during Fire Overhaul,” AIHAJ (May 2000). Note: The National Fire Protection Association’s safety recommendations for firefighters include a reference to this study.

“Adverse Respiratory Effects Following Overhaul in Firefighters,” Journal of Occupational and Environmental Medicine (May 2001).

“Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction,” Underwriters Lab (