Firefighter PPE: Designing for contamination control
Seeking a new design approach that focuses on preventing contamination in the first place, plus allowing for effective decon
With the advent of standards for firefighter PPE in the mid-1970s, the principle concern at the time was ensuring clothing flame/heat-resistance and durability.
When the first edition of NFPA 1971: Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting was released in 1981, there was no insulation test. Instead, thermal insulation was assessed by the overall thickness of the composite. Thermal protective performance (TPP) testing as we know it today was not introduced until the 1986 edition.
As both material and evaluation technology improved, additional criteria and test methods were incorporated into the standard to address the range of other protective elements, including helmets, gloves, footwear and hoods. However, it soon became apparent that insulation for the sake of increased protection created other issues, such as heat strain and physiological stress. Efforts by the IAFF and other organizations led to the establishment of total heat loss (THL) as a way of balancing thermal insulation with imparted thermal stress by the clothing system.
Along the same path, firefighter protective clothing now includes a moisture barrier or other barrier layer, which is intended to prevent the passage of hot water, infectious liquids and fireground chemicals. In a large way, this layer – found in garments, gloves and footwear – helps prevent contamination of the firefighter. But firefighters still become contaminated by the passage of particulates and fire gases through interfaces and other gaps in the ensemble that cause exposure of clothing interior layers or the firefighter’s skin. Many of our past articles have highlighted these contamination pathways and indicated the need for overall assessments of ensemble performance coupled with better attention to the design of interface areas. Manufacturers have endeavored to meet these challenges by designing novel clothing systems, which offer overall better integrity and reduce firefighter exposure to both smoke particulates and liquids.
In today’s firefighter PPE world, the fire service seeks a balance between protective qualities (heat insulation, physical hazard resistance, and contaminant exposure) and its impact on the firefighter (thermal burden, mobility, and overall ergonomics). As a result, clothing systems are evolving towards the lightest weight, the most flexible, and imparting the least stress on the firefighter without compromising protection. Yet, we believe there is a third factor that now needs to be considered in how materials are developed and clothing is designed.
Wanted: A new factor to inform PPE development
The fire service has also become increasingly aware that clothing itself becomes a source of contamination after its exposure, and many departments recognize the value of frequently cleaning, at least their garments and hoods. Thus, it would seem that the use of barriers in clothing with better attention to interfaces and regular cleaning would make clothing contamination-resistant.
Still, while various design features and materials reduce the transmission of contamination, moving from the exterior to the interior of clothing, this does not necessarily mean that firefighter PPE is contamination-resistant. Sure, firefighter PPE functions to prevent most exposures using practical approaches, but the mere fact that PPE contamination does occur seems to be a foregone expectation. What if it was possible to make clothing pick up less contamination and remove that contamination much easier than currently exists?
If we examine the current criteria that relate to how easily clothing is cleaned, there are only a few requirements. Outer shell materials are required to have relatively low water absorption. Up until the last edition of NFPA 1971 (2013), shell materials were allowed to absorb 30% of their water weight and still be acceptable. That limit was reduced to 15% in 2018, but only for water. In fact, most materials show water weight gain at levels lower than 5% when washed repeatedly under harsh conditions. The concern for going lower has become an issue because material suppliers fear that limitations on finishes due to the use of controversial chemicals put onto these materials will make it impossible for these materials to offer lower levels of water absorption-resistance. It is further expected that less-effective fabric finishes will also mean that clothing surfaces will also absorb much larger quantities of various hazardous fireground chemicals or make these chemicals harder to remove through cleaning. The absence of any standardized criteria within NFPA 1971 to address how readily clothing materials pick and retain expected contaminants makes it difficult to assess this specific need for firefighter PPE.
In late-2019, NFPA 1851: Standard on Selection, Care, and Maintenance of Protective Ensembles for Structure Fire Fighting and Proximity Fire Fighting was significantly revised to include a set of criteria imposed on independent service providers (ISPs) that requires their verification of advanced cleaning processes. Using a range of organic chemicals and heavy metals, minimum cleaning efficiencies were established at 50%, recognizing that the new requirement provides an initial benchmark for later improvements.
As these requirements are being applied in the first part 2020, removal rates for the target chemicals for most facilities range from 50 to 75%. It is recognized that some chemicals are difficult to remove given their persistency, low volatility and low water solubility. It is uncertain if cleaning efficiencies might be affected with changes in materials that lessen repellent finishes. Yet, without any form of requirement for selecting materials that are easier to clean, contamination removal-resistance cannot be assessed until after it is made and becomes an issue for the fire department and the cleaning companies.
The 2018 edition of NFPA 1971 also requires the helmet ear covers be capable of being detached from and reinstalled on the helmet per the manufacturer’s instructions within a period of 20 minutes. This is the only requirement of its type and is supposed to enable easier cleaning for that textile-based component of helmets. This could be especially helpful since helmets are rarely cleaned. Of course, certain other portions of the helmet – the retention system (chin and nape straps), head suspension, and sweatbands – can also be a continuing source of contamination that comes in contact with the firefighter’s head. Similar concepts have been promoted for SCBA that permits easier removal of the backpack harness and straps that permit separate cleaning of these components.
Still, not all clothing items are easy to clean. There have been ongoing concerns that cleaning of gloves and footwear, expected to be some of the more contaminated elements of the firefighter ensemble, are also the dirtiest and least effectively cleaned. Most often, these clothing items are hand-washed, and it is unknown if exterior contamination is transferred to the interior of these elements when certain washing techniques are used.
Outside of these requirements, there is very little to address the ease of cleaning or determining the amount of contamination that firefighter PPE picks up during a fire or emergency event. There is no doubt that firefighting is a very dirty job, given the nature of the fireground environment. Yet, given that contamination control is now a much larger issue, it would seem sensible that additional assessments and criteria be implemented that begin to better address ways for lessening contamination as it occurs on the fireground and in allowing its removal.
A proposal for change in firefighter PPE
The firefighter PPE industry has a good grasp on thermal insulation and general protection approaches in clothing and materials. Over the last several years, as supported by several research initiatives, there have been an increased understanding of fire service ergonomics, especially focusing on heat strain caused by the wearing of PPE under various environmental conditions. The interaction of this knowledge has resulted in more advanced clothing and equipment that better fits the firefighter, results in less stress, and promotes greater overall functionality. A third factor influencing design and development of PPE is needed that addresses contamination control for preventing the contamination in the first place, and when present, allowing for effective decontamination.
The very simplified approaches provided in the NFPA standards to date starts PPE along this path, but more is needed to properly guide clothing and equipment design toward contamination control. We envision new tests of materials in NFPA 1971 that include ensuring low levels of restricted hazardous substances, evaluating performance for retaining specific chemicals, and also assessing the ability to remove contaminants.
Material tests need to be coupled with product designs that provide ways of contamination avoidance or ease of cleaning in ways that offer improvements over current products. These may include some parts to be disposable or complete redesigns of certain clothing items, including how these items elements interface with firefighters to, for example, permit improved doffing without contaminant transfer.
Finally, contamination control through the times that PPE is worn, its handling, and cleaning/decontamination need to be further improved. Although it does not seem possible now, structural firefighting may become more like hazmat response in a manner. Perhaps this philosophy will drive the approach of designing PPE for contamination control.
[Read next: Firefighter PPE contamination: What you need to know]
Note: The views of the author do not necessarily reflect those of the sponsor.