Research results: The impact of increased laundering on structural PPE
Fire service researchers evaluate impact of laundering on tear and seam strength, THL and TPP, flammability, and liquid and viral penetration
Your structural firefighting protective ensemble, your PPE, is designed to protect you during interior structural firefighting.
NFPA 1971: Standard on protective ensembles for structural firefighting and proximity firefighting specifies that to be compliant, your PPE must be capable of providing some limited measure of protection from the following hazards:
- External thermal threats (heat from the fire)
- Internal thermal threats (the heat your body generates)
- Liquids penetrating the PPE and reaching you (everything from water to biological hazards)
- Physical hazards (e.g., cuts, scrapes, abrasions)
And, of course, in the most extreme circumstances, give you a fighting chance of surviving a flashover.
In the last decade or so, we've been made keenly aware of the threat that our PPE can present by harboring the chemicals, chemical compounds and carcinogens present in the smoke and other contaminants generated by the burning structures you enter to search for victims and suppress fires. The increased awareness to that exposure has led many fire departments to take a more proactive approach to reduce that risk. Those measures typically include initial contaminant reduction (ICR) on site and more frequent laundering of PPE back at the station.
BUT AT WHAT COST?
What effect do these increased cleaning efforts have on your PPE? Can on-site ICR and more frequent laundering be having a detrimental effect on your PPE?
Those are the questions that Gavin Horn, Steve Kerber and other researchers sought to answer. In the July report Impact of Repeated Exposure and Cleaning on Protective Properties of Structural Firefighting Turnout Gear, published in Fire Technology, those researchers –representing the Illinois Fire Service Institute, UL Firefighter Safety Research Institute, UL LLC, National Institute for Occupational Safety and Health (NIOSH) and Skidmore College –conducted a series of tests to evaluate how increased laundering affects the following performance characteristics of PPE:
- Flammability to determine the vertical flame resistance of turnout gear materials
- Thermal Heat Loss (THL). THL measures how well the PPE garment allows heat and moisture vapor to transfer away from the wearer, thus helping to reduce heat stress.
- Thermal Protective Performance (TPP). The TPP rating, when divided in half, represents roughly the approximate number of seconds until a firefighter would suffer a second-degree burn.
- Permeability. Three-part testing that evaluates the capability of the moisture barrier and seams to: 1) keep the firefighter dry from external pressurized water; 2) resist penetration of liquids meant to be representative of those commonly encountered on the fireground; and 3) keep bloodborne pathogens from coming in contact with the firefighter.
- Fabric Tear Resistance. The Tear Resistance Test measures the ability of the fabrics used in construction to resist further tearing when a small tear occurs. It is also a test of the strength and durability of the fabric.
The team’s goal was to characterize the impact on these select performance characteristics of PPE (compliant with NFPA 1971) after repeated exposures to the products of combustion from the burning of household combustibles followed by different cleaning techniques (laundering, wet decontamination and dry decontamination).
SETTING UP THE TESTS
The research team used a Conex box to construct a Fire Exposure Simulator (FES) capable of producing smoke exposure approximate to that firefighters work in while doing interior structural firefighting. The FES consisted of three separate compartments of equal dimensions:
- The middle compartment served as the “burn room” where a popular model of commercially available sofa was burned to produce heat and smoke. All doors to FES were kept closed, and the only ventilation to the burn room came from existing leakage paths in the chamber.
- The other two compartments were designed to simulate smoke conditions that firefighters would be exposed to by piping in smoke and heat from the center burn room.
The researchers used 22 new sets of structural firefighting PPE of identical materials and construction which were designed for use with full-sized mannequins. The outer shell and thermal liners were selected from among the most common PPE options on the market at the time the mannequins were obtained.
The study also included sets of PPE, identical to those used with the mannequins, that were not exposed in the FES; those sets were also laundered and served as the control group.
Most of the PPE was manufactured using a combination of a zipper and Velcro closures for the front of the coat and pants. A subset of gear was produced using hook and “D” closures to enable the researchers to study what impact – if any – the coat closure system would have on the PPE during laundering and drying.
Before placing the test mannequins in the FES, each was dressed in open air. In addition to the coat and pants, each mannequin had an SCBA facepiece, helmet and protective hood put in place, along with a belt placed just above the hips to simulate the waist belt of an SCBA unit.
CONDUCTING THE TEST
The research team placed 11 mannequins in each of the two test compartments in a standing position and exposed them to the smoke and heat for varying amounts of time. During the test period, the mannequins were moved around the room to more evenly expose all the test mannequins to the smoke exposure and replicate firefighters moving around in a structure.
Following the test exposure, each set of PPE (including those in the control group) was laundered using one of three procedures:
- Laundered according to NFPA 1851: Standard on Selection, Care, and Maintenance of Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting (2014 Edition; most current edition at the time of the study) using a front-loading extractor with warm water and acceptable detergent. Following laundering, the garments were dried using a forced-air cabinet with air circulating at 105 degrees F (40.5 degrees C). The same laundering procedure was used for outer shells and inner liners, though separate machines were used for each component through the study.
- Wet decontaminated using a 2-gallon (7.6 liter) pump sprayer filled with a mixture of water and about 10 mL of dish soap. The PPE was pre-rinsed with plain water, sprayed with the soap/detergent solution, scrubbed with soap/detergent solution using an industrial scrub brush, and then rinsed with clear water until no suds remained.
- Dry decontaminated using an industrial scrub brush to remove surface debris and contaminants from the gear.
For garments cleaned using either Option #2 or #3, the garments were hung on coat hangers in a vented PPE storage container at ambient temperature and humidity until the next burn scenario.
Once dried, the sets of PPE were redeployed for another round of testing.
This process was repeated using a protocol that included repeated simulated fireground exposures (between 0 cycles and 40 cycles) for each set of PPE.
EVALUATION OF PPE FABRIC
Upon completion of the exposure and laundering cycles, the research team evaluated fabric samples using the performance testing criteria specified in NFPA 1971 for tear strength, seam strength, THL, TPP, flammability, liquid penetration and viral penetration.
The researchers identified the following as key outcomes from the study:
- Repeated laundering treatment (Option #1) reduced the tear strength of the outer shell and thermal barrier compared to the new samples and more so than either the wet or dry decontamination treatments.
- After 40 laundering cycles, outer shell tear strength and seam strength dropped below those levels specified for new PPE in NFPA 1971.
- Wet soap decontamination had a negative impact on moisture barrier seam strength than laundering but did not significantly impact flammability.
- There was a reduction in the THL for all samples with a cleaning treatment; TPP increased in the PPE that was machine laundered and dried. The researchers postulated that the latter might be attributed to the “fluffing” of the PPE’s thermal layer during the tumbling action of the machine drying.
- PPE constructed with hook and “D” closures had lower outer shell tear strength and reduced performance in the liquid penetration test. Here the researchers felt that the hook and “D” closures might be a contributing factor for PPE that was machine laundered and dried.
The researchers found few notable differences between the exposed/laundered PPE and the non-exposed/laundered PPE. This led them to conclude that the impact of simulated fireground smoke exposure on the NFPA 1971-based performance testing was minimal compared to the impact of repeated laundering. (Note: The study’s fireground exposure did not include a mechanical challenge, such as scuffing or abrading, to the PPE as would be expected from firefighters moving and working on the fireground.)
CONCLUSIONS – AND QUESTIONS
The researchers added that it is important to note that many of the performance tests contained in NFPA 1971 (e.g., tear resistance and seam strength) specify that the test garments be pre-conditioned (laundered) for only five wash and dry cycles.
According to the researchers, the study findings suggest the potential value for NFPA to increase the number of wash/dry cycles used to pre-condition PPE elements prior to undergoing the performance test requirements of NFPA 1971. They felt that such an increase would provide a more realistic pre-conditioning of PPE garments prior to NFPA 1971 compliance testing. And it would give fire departments a better indication of the impact they could expect from their own increased laundering of PPE. That’s the big takeaway from this research effort.
Fire service leaders must stay abreast of future developments for cleaning of firefighting PPE. What sort impact is increased laundering going to have on the 10-year service life for structural firefighting PPE as specified in NFPA 1851? What affect will shorter PPE life cycles have on fire department budgets? What alternatives are being considered for keeping PPE safe beyond laundering, wet decontamination or dry decontamination? Some good questions that hopefully future research can answer.