In the FireRescue1 webinar “Gear up for PPE changes,” we announced that one of the more significant transformations in the upcoming revision to NFPA 1971 standard for structural firefighting protective clothing was the full industry transition to mandatory particulate-blocking hoods.
If this is indeed included in the next edition, we will consider this to be a huge change. After all, over the past 30-plus years that firefighters have worn hoods, these hoods have almost universally been two to three layers of knit material to provide insulation to those areas of the firefighter’s neck and face that were not fully protected by other gear. Now, potentially beginning in 2024, only hoods that completely incorporate a particulate-blocking layer will be permitted to be certified for structural firefighting. In addition, certain other characteristics of these hoods will change as the result of modifications to the NFPA 1971 hood criteria.
Here we will explain how the use of hoods came about and why this new direction is being considered for inclusion.
Fire hoods: A short history
Fire hoods of one sort or another have been around for quite a while. Some firefighters began wearing hoods made of leather back in the early 1900s, but as fire gear improved during the last 50 years, use of a balaclava or ski-hood-like design became more prominent, though not frequently worn. Advancements in other parts of the protective ensemble led to a greater need to protect the head and face, particularly as firefighters could enter deeper into and stay longer in structural fires given modern technical materials and clothing designs.
While the standard knit hood preceded its standardization as part of NFPA 1971 in 1991, the formal adoption of fire hoods as an interface component was embraced at least 10 years earlier. Some holdouts for wearing hoods remained, as these firefighters believed that their ears were an “early warning device” when they were on the fireground too long. Ultimately, the use of knit fire hoods by larger metropolitan fire departments further paved way for their more routine use.
Protective hoods became defined as an “interface component” primarily because the clothing item was designed to provide protection at the juncture of several other protective ensemble elements, namely the fire helmet (with ear covers), SCBA facepiece, and protective coat collar. Coming up with a product that could be integrated into this complex body area was best addressed by a “one-size fits most” stretchable knit product that could fill the “gaps” in protection.
Protective hoods have subsequently become a consistent part of the overall structural firefighting protective ensemble where requirements were defined for their design and performance, including areas of coverage, thermal insulation, flame resistance, heat resistance, thermal shrinkage, cleaning shrinkage, and fabric and seam strength. In the last rendition of criteria for these products within NFPA 1971 (2018), one area of focus was placed on the size and retention of the face opening dimensions.
The genesis for improved face/neck particulate protection
From 2013 to 2015, separate research conducted by the National Institute for Occupational Safety and Health (NIOSH) and the International Association of Fire Fighters (IAFF) found that the face and neck area of firefighters in smoke or simulated smoke conditions was one of the most contaminated areas of the firefighter’s body. As part of a NIOSH Health Hazard Evaluation Program, researchers ran several firefighters through simulated fireground exposures to measure polycyclic aromatic hydrocarbon (PAH) and other chemical contamination levels on different parts of their body. From this study, they concluded that the skin in the head and neck area were the most likely to be contaminated with soot and fire gases. The IAFF then conducted an evaluation involving a sophisticated fluorescent particulate exposure test of a full garment ensemble and was able to visually show the highest levels of contamination in areas of the test subjects’ face and neck that were not covered by the facepiece or blocked by the chin strap of the helmet.
Manufacturers rushed to develop new hood products that included a variety of intermediate layers that would effectively block soot particles from penetrating the knit materials most commonly used in fire hood construction. This led to a range of new products, many introduced in 2016 following the NIOSH and IAFF research.
Work on a new category of protective hood with particulate protection was undertaken to define the design and performance characteristics of this new class of hoods. Ultimately, the responsible committee introduced criteria for the minimum areas of the hood that required particulate-blocking layers and added test requirements for particulate-filtration efficiency and the application of a total heat loss (“breathability”) test to balance the effects of including a barrier layer on the head. With the promulgation of the 2018 edition of NFPA 1971, hoods could optionally be certified to the additional particulate protection criteria. Several manufacturers offered these hoods, and a large proportion of departments opted for this additional protection.
The transition to updated hood requirements
When the committee concluded its work on new requirements for the particulate-blocking hood, it was recognized that the prescription of this new product type was still evolving – and there was still much to learn. This is a principal reason why particulate-blocking hoods were presented as being optional. The NFPA, manufacturers, fire service leaders and researchers endeavored to better understand how products certified to the additional particulate protection criteria worked in contrast to conventional knit hoods and to determine if more gaps in the knowledge of their production should be filled.
In 2016, a substantial project was started by North Carolina State University under a Department of Homeland Security FEMA grant to examine several attributes of hoods, including their overall thermal insulation, impact on heat stress, durability and, most importantly, ability to attenuate exposure to harmful fireground soot particles. Research conducted over more than three years yielded some interesting findings when comparing different hood types and materials. For example, particulate-blocking hoods were found to offer 10 times more protection than comparable knit-only hoods. Further, the differences in thermal protection and comfort between conventional knit and particulate-blocking hoods was found to be minimal, and were more related to the number of layers in the hood’s construction rather than presence of a particulate-blocking layer. Separate research in a Fire Protection Research Foundation project showed little difference between particulate-blocking and conventional knit hoods for removal of chemical contaminants during washing.
Additional information about the effectiveness of particulate-blocking hoods has also been learned through firefighters’ experience using these products at structural fires. This experience has shown lower levels of skin exposure to fire particulates.
As a result of this knowledge, the technical committee responsible for NFPA 1971 proposed mandating that future hoods must meet particulate-blocking requirements. Additional changes might also require testing of hood seams for particulate penetration, extend the area of the particulate-blocking layer coverage to all parts of the hood, apply increased durability rigor of the hood’s particulate protection performance, and offer hoods in multiple sizes to achieve fit, if necessary.
Implications of the future NFPA 1971 standard
Shifting the fire service PPE industry from conventional knit to particulate-blocking hoods, along with other proposed changes affecting the new class of hoods, is expected to be a positive change but one that may also create some concerns:
- Particulate-blocking hoods are more expensive than conventional hoods. This difference in price shifts hoods from a commodity PPE to a more premium product. This can become more of an issue as replacement frequency increases due to additional cleanings.
- While many particulate-blocking hoods seem similar in fit and conformity to the firefighter’s head, some of these newer hoods do not have the same elasticity or stretch as knit-only hoods due to the material used in the particulate-blocking layer.
- Additionally, the extension of the particulate-blocking layer into nearly every area of the hood may create sizing issues for some hoods on some individuals. This means hoods may not be “one size fits most” anymore, and like other PPE, firefighters will need to manage their hood selection based on available sizes. For departments that issue hoods to individual firefighters, this would not be an issue; however, where some departments adopted practices for issuing fire hoods at the scene and collecting them afterwards for cleaning, additional oversight will be needed. The NFPA committee has attempted to standardize sizing by using new requirements to define fit based on accepted industry head forms.
- The requirement to now apply particulate-blocking capabilities not just to the base material but also the seams means that some hood manufacturers may now have to use seam tape or other methods to seal stitching holes that could be a source of particulate penetration. For some products, this could result in hoods becoming stiffer, therefore requiring more available sizes. Regardless, several hood manufacturers will need to address these new requirements with modifications to their hood designs, materials or both to achieve the new requirements, meaning that the available mix of products will change again.
- Total heat loss was a requirement only pertaining to the newer particulate-blocking hoods since 2018. With the possible changeover to mandatory particulate blocking for all structural firefighting hoods (hoods for proximity firefighter are exempted from particulate blocking criteria), the THL requirement will affect the range of hoods and layers that historically have been offered to the fire service. One consequence of this change is that heavier hoods, particularly those likely to be used by instructors, may no longer comply with the proposed new edition of NFPA 1971. This matter was discussed, but the committee felt that minimizing the thermal burden on firefighters was of greater importance.
Time to contemplate change
Given that the new edition of NFPA 1971 won’t become effective until the middle of 2024 at the earliest, both fire service and industry leaders have time to determine how these changes in hoods may affect their operations going forward.
Note: The views of the author do not necessarily reflect those of the sponsor.