Firefighters face dangerous heat inside turnout gear, even during winter

BUFFALO, N.Y. – Anyone who has seen a winter fire can picture the scene: Firefighters battling dangerous blazes wrapped in heavy insulated clothing to protect them from open flames, smoke, hazardous chemicals and more. The frigid external temperatures are a stark contrast with the rising core temperatures of the people inside the protective firefighting clothing, known as turnout gear.

Now, two clinical assistant professors from the Jacobs School of Medicine and Biological Sciences at the University at Buffalo are sounding a different safety alert: Firefighters wearing turnout gear face heat stress, even in freezing temperatures.

"Despite the incredibly cold temperatures that we occasionally have in Western New York, we still need our firefighters to be concerned about heat injuries, and make sure that they focus on cooling their core temperatures during the winter months,” says Andrew R. Poreda, MD, clinical assistant professor in the Department of Emergency Medicine in the Jacobs School of Medicine and Biological Sciences.

Poreda and Kyle Kelleran, PhD, also assistant professor in the Department of Emergency Medicine, study how firefighters’ bodies respond while working in the cold. They have published research on the subject, including a study “Physiological Impacts of Cold Conditions during Moderate Intensity Activity while wearing Firefighter Protective Clothing” in the journal Prehospital and Disaster Medicine in November.

“Standard guidance from the National Fire Protection Association [NFPA] would tell you that any firefighters with cold-related stress should add additional warming layers, blankets, or use other methods to regain normal body temperature,” says Poreda. “Our study adds subtlety to this advice. 

“Most firefighters might not be at risk of cold-related stress, or if they are, it's isolated to their extremities in the form of frostbite. Instead, the NFPA rehab section should still be focused on the heat-related stress like hyperthermia that can occur, and work to cool their firefighters and redistribute the heat from their core to their extremities.”

In their study, the researchers observed 14 certified interior firefighters as they performed moderate-intensity work in full turnout gear. One session took place in a 68-degree Fahrenheit chamber and the other in a 17-degree chamber.

Each session included two, 20-minute work intervals separated by a brief rest period and followed by 20 minutes of rehab. Throughout the protocol, the researchers measured core body temperature, mean skin temperature, hand and finger temperatures, heart rate, respiratory rate, perceived exertion and thermal comfort.

Based on their findings, they make the following recommendations:

• Do not rely on comfort or self-assessment as a marker of readiness. Objective data must guide return-to-work decisions.
• Balance frostbite and heat stress prevention; both hazards can coexist in winter operations.
• Maintain hydration protocols even when firefighters do not feel thirsty.
• Build rehab areas that are dry and sheltered but not excessively warm.
• Ensure that firefighters fully recover before redeployment, regardless of how they feel.

The last recommendation is important, Poreda says, because a firefighter may feel fully recovered long before they actually are. Poreda stresses that objective criteria, such as vital signs, temperature normalization and other measurements emphasized by the NFPA, should outweigh firefighters own perception of when they’re ready to return to work.

The researchers recommend additional studies for how wind, snow, moisture and contact with cold affect firefighter safety in winter operations.