NIST researchers measured a 20,000-cycle abrasion protocol and a 260 °C (500 °F) five-minute heat exposure on firefighter gear, and found that wear and tear significantly increased measurable PFAS levels in structural hoods and gloves — but decreased them in wildland gear. The study, published this week as NIST Technical Note 2375, is the latest in a series the institute has produced since 2021 under a congressional mandate.

Congress tasked NIST with measuring PFAS in firefighter equipment through the 2021 National Defense Authorization Act. "At that time, there were no measurements of how much PFAS was in this equipment," said Rick Davis, project leader for NIST's reports on PFAS in firefighter gear. "Making those measurements is a crucial starting point for understanding and addressing the problem."

Why PFAS is in the gear at all

Water conducts heat, so protective garments must keep firefighters dry. Per- and polyfluoroalkyl substances — the "forever chemicals" also used in nonstick pans and raincoats — repel liquids exceptionally well, which is why manufacturers treat firefighter clothing with them for moisture resistance. Exposure to high PFAS concentrations has been linked to cancer, and studies suggest firefighters have higher cancer rates than the general population, though not necessarily because of PFAS specifically. The NIST studies do not assess health risk; they supply the concentration data that toxicologists and epidemiologists need to do so.

What did the tests involve?

The team examined three equipment classes: wildland gear (lightweight coat, shirt and pants for wildfires), and structural hoods and gloves used in building fires. A previous study measured PFAS in these materials new; this one applied field-realistic stresses. The treatments matched each item's expected duty cycle:

• Abrasion: hoods and wildland gear rubbed with a wool pad at standardized speed and pressure for 20,000 cycles, or until the fabric failed. Gloves were excluded — their thick outer layers are unlikely to wear through in regular use.
• Heat: hood and glove samples held in a convection oven for five minutes at approximately 260 °C (500 F), simulating conditions inside a burning building. Wildland gear was excluded because it is not rated for that heat.
• Weathering: wildland gear exposed to intense bouts of UV light and moisture to simulate long-term outdoor exposure.

After each treatment, the researchers quantified PFAS concentrations by liquid chromatography–mass spectrometry, targeting 56 of the thousands of known PFAS compounds — the most well researched and most relevant to health concerns.

What did the measurements show?

Results split by gear type:

• Structural gloves showed increased measurable PFAS after heat treatment.
• Structural hoods showed increased measurable PFAS after both abrasion and heat treatment.
• Wildland gear showed decreased measurable PFAS after both abrasion and weathering.

The direction of change may reflect two different mechanisms: wear and tear releasing more PFAS from the fabric, or chemical transformation of PFAS into different PFAS types — raising or lowering the specific 56 compounds the method was designed to catch. The study cannot distinguish between the two from these data alone.

Together with the earlier baseline study, the reports establish a standardized measurement approach for tracking PFAS in firefighter equipment over time. The NIST team plans to extend the work to other potentially dangerous chemicals, including fluorine and bromine. Several equipment manufacturers have already begun selling gear advertised as PFAS-free — a claim that currently lacks a standardized verification basis.

"Accurate and reliable measurements will continue to be important as the industry changes," said Andre Thompson, the study's lead author. "The work NIST has done could help set a baseline for how these new products can be measured and compared under a variety of conditions."

The open question for procurement offices and standards bodies is whether "PFAS-free" claims will be validated against a NIST-style stressed-condition protocol — because as this study shows, what a garment measures new tells you little about what it measures after 20,000 abrasion cycles or five minutes at 260 °C.