Heat Resistance in PPE: How New Materials Are Improving Firefighter Safety

Advancements in heat-resistant materials and regulatory updates are enhancing the safety and health of firefighters by improving their gear's performance and reducing harmful chemicals.

• By Haley Polly
• Oct 04, 2024

From the outside, firefighter response gear doesn't look terribly high-tech. The coats, pants, gloves and boots don’t differ much from regular versions of the same items. But the makeup of this clothing is highly sophisticated, representing intense manufacturing and testing processes that have been painstakingly researched and improved upon over decades. 

The base materials are not new: Kevlar and Nomex, two common fibers in flame-resistant clothing, were first developed in the 1960s. But these clothes’ fiber blends and construction are always in flux. Wildland fire gear in particular needs continuous upgrades as forest fires burn hotter and more frequently.

Let’s review the basic materials common in firefighter personal protective equipment (PPE) and how those materials are changing. Then let’s also note new regulations that are aimed at removing cancer-causing chemicals from firefighter gear.

Structure and Wildland Fire Gear: Flame-Resistant Fibers

Firefighter gear is made of various blends of flame-resistant (FR) fabrics, meaning they do not melt or drip when exposed even to intense thermal environments.

The PPE for structure firefighters – also called “turnout gear” – is made of three fabric layers:

• A thermal liner, allowing the wearer to feel less heat
• A moisture barrier, to wick sweat away from the wearer while protecting them from outside moisture, including chemicals like battery acid, antifreeze and other hazards
• An outer shell to protect the wearer from direct flame

Wildland fire gear is typically different. Fighting forest or brush fires is an arduous process that can stretch out over many hours. So the heavy, multi-layered gear of a structure firefighter is too exhausting to wear. Wildland firefighters need lighter, more comfortable clothes. These are often a single layer of FR fabric that provides thermal protection without too much weight.

Typically, wildland fire gear is made up of specially made pants, shirt and overclothes. Or the firefighter may use a full-body jumpsuit called an extrication suit.

These clothes are constructed to provide as complete coverage as possible, with features like stand-up collars to protect the neck and closures to seal up the cuffs. But the real heat resistance is in the fibers themselves. Most wildland fire gear is made of several common types of FR blends, such as Sigma, TecaSafe or Synergy. These proprietary fabrics usually blend fibers for different levels of flame resistance, breathability and durability. 

Although manufacturers are always upgrading the specific blends of FR fabric, the best-known fibers that form the basis of these uniforms date back decades, when scientists first developed Nomex and Kevlar.

Both are inherently flame-resistant, meaning these FR properties cannot decrease with time, use or repeated washing. The key difference is that Kevlar has increased strength. The material is famously used in bullet-proof vests.

New Construction for Better Protection

Manufacturers are always seeking to lower the heat stress on firefighters. That means examining every aspect of the clothing, down to the microscopic fibers. 

With new fabric blends emerging for structure turnout gear, the latest designs provide more stretch in the fabrics for increased comfort, and different layers are emphasizing new blends. Outer layers of turnout gear incorporate more Kevlar in the outer shells for increased strength and Nomex in the inner lining for better durability. 

As for wildland fire gear, contributors to the Centers for Disease Control and Prevention noted that PPE construction is at the core of new improvements. 

Wildland PPE is constructed to allow for an air gap to keep FR fabrics off the skin. That helps the wearer stay comfortable without compromising radiant heat protection. “Unfortunately, this same design requirement is causing serious sizing issues for smaller and larger individuals,” the CDC noted. That’s why there are health disparities among wildland firefighters who don’t fit the “typical” sizing.

Regulatory agencies such as the National Fire Protection Association (NFPA) are working on standards that will encourage better fabric performance for all wildland firefighters. 

Updates to FR Material: Safer for the Long Term

The flame resistance of these materials is truly impressive and has no doubt contributed to firefighter safety. Now, there's a new frontier in firefighter health: lowering the chemical composition of PPE to remove cancer-causing chemicals. This step is urgently required to ensure that firefighters stay safe long after they’ve hung up their helmets. 

The past several years have brought new attention on the role of per- and polyfluoroalkyl substances (PFAS) in turnout gear. Studies raised the alarm on the cancer-causing potential of these chemicals, which have been found in all three layers of turnout gear. This was especially worrisome because it connected to another longtime concern about firefighter health. Firefighters have a 14 percent higher chance of dying from cancer compared to the overall population.

New regulations from the NFPA and other organizations raised the standards for PPE. New requirements mean manufacturers must:

• Measure PFAS levels.
• Apply more stringent criteria for meeting acceptable PFAS quantities.
• Limit other restricted substances, such as lead.

Heat resistance in PPE is important but only part of the battle for firefighter safety. For the future, firefighters need turnout and wildland fire gear that will protect them from heat and flames as well as keep them healthy for decades to come.