As concern grows around fireground contaminants, particulate barriers have become a popular addition to turnout gear. While these added layers are designed to reduce exposure, they also come with a trade-off: reduced breathability and increased heat retention, which can contribute to heat stress.  

So the question is simple: is the extra barrier actually necessary?

To find out, Fire-Dex partnered with RTI International, an independent nonprofit research institute, to study how particulates enter turnout gear and whether additional barriers improve protection. The results were later verified by UL Solutions, confirming they meet industry standards for particulate protection.

What the Testing Looked Like

Testing took place in a controlled particulate chamber using full Fire-Dex PPE, including AeroFlex® turnouts, a particulate-blocking hood, gloves, boots, and helmet. A firefighter performed simulated fireground movements over two 10-minute cycles while exposed to a consistent level of particulates.

RTI evaluated multiple configurations, including:

• SCBA harness engaged; no particulate blocking material at the coat–pant interface
  
  
  

• SCBA not worn; particulate blocking material at the coat–pant interface
  
  
• SCBA harness engaged; particulate blocking material used in the pants only
  
  

After each test, researchers analyzed particulate contamination on the skin using specialized imaging technology.

What They Found

The most significant finding was the role of the SCBA harness. When properly engaged, no particulate exposure was detected on the torso, even without particulate-blocking material at the coat–pant interface, with UL verification confirming total exposure below 1 microgram. RTI also found that adding this material did not improve protection, as the SCBA harness itself created an effective seal at the interface during interior operations, making the extra layer unnecessary.

UL Verification 1641 later confirmed that the ensemble met particulate ingress expectations when worn with SCBA as intended.

However, the study also reinforced that protection is not one-size-fits-all. RTI documented particulate contamination on the legs when the pants did not include particulate blocking material, demonstrating its role in limiting lower body exposure.

The testing also highlighted the effectiveness of AeroVent® Technology in AeroFlex® gear, which allows heat and moisture to escape while preventing particulate ingress through strategically designed vent zones.

Why This Matters

These findings challenge the long-standing assumption that more layers always mean more protection. If the SCBA already seals the coat–pant interface, adding extra material in the coat may be unnecessary and could actually increase risk by trapping heat and limiting the body’s natural cooling process.

Reduced airflow increases internal heat and humidity, which is critical because heat stress is the leading cause of firefighter line-of-duty deaths (LODDs). Any unnecessary restriction in the coat that increases heat burden can directly compromise firefighter safety.

A Smarter Approach to Protection

AeroFlex® turnout gear avoids adding unnecessary restrictive layers in the coat, which helps improve heat management.

Using a zoned design that balances breathability and particulate defense, VaporLite® Panels are strategically placed in high-heat areas like the underarms, inner thighs, and behind the knees—where the body naturally produces the most heat and sweat. AeroVent® Technology works within these zones, using vents to push hot, humid air outward through all layers of the gear as the firefighter moves, while still blocking particulates from entering.

By allowing trapped heat and moisture to escape, AeroFlex® helps keep the body cooler during intense activity. And by relying on a properly engaged SCBA harness to seal the coat–pant interface, it eliminates the need for added bulk in the coat, helping firefighters move more freely, manage heat more effectively, and maintain protection where it matters most.

The Bottom Line

Independent testing by RTI International, verified by UL Solutions, demonstrates that a properly engaged SCBA harness effectively seals the coat–pant interface and prevents particulate exposure to the torso. Adding a barrier in that area does not enhance protection, but it can reduce breathability.

For firefighters, that means protection doesn’t have to come at the expense of performance. With the right design, you can have both.