As concerns grow 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 a 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 testing revealed that effective particulate protection depends on how the full gear system works together.

At the coat-pant interface: A properly secured SCBA harness created an effective seal during interior operations. Researchers detected no exposure on the torso, even without particulate-blocking material at the interface. UL verification measured total exposure at less than 1 microgram. RTI found that adding particulate-blocking material in this area did not further improve protection. UL Verification 1641 later confirmed that the ensemble met particulate ingress expectations when worn with SCBA as intended.

On the lower body: Particulate-blocking material still played an important role. RTI detected contamination on the legs when the pants didn't include the material, showing its value in limiting lower-body exposure.

Through the vent zones: AeroVent® Technology in AeroFlex gear allowed heat and moisture to escape while preventing particulate ingress through strategically designed ventilation areas.

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, confirmed that a properly secured SCBA harness effectively seals the coat-pant interface and prevents particulate exposure to the torso. An additional barrier did not enhance protection and could reduce breathability.

For firefighters, the result is effective particulate protection without sacrificing the breathability needed to perform on the job.