It is truly encouraging to learn that fire departments are increasingly implementing on-scene gross decontamination practices following structural fires as part of progressive programs to address contamination control.
In preliminary information from a survey administered by the NFPA’s Fire Protection Research Foundation (FPRF) aimed at better understanding the application of cleaning techniques across the range of fire service PPE, 60% of the survey respondents indicated that some form of on-scene gross decontamination was in place within their department.
Why preliminary exposure reduction (PER)?
In NFPA 1851: Standard on Selection, Care and Maintenance of Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting, the term preliminary exposure reduction (PER) is used in lieu of the more common industry term gross decontamination because it more accurately describes the activities specified by NFPA 1851 for initially addressing contaminated firefighting protective ensembles and ensemble elements.
It is understood that while PER is likely to remove some contamination from the surface of the protective ensemble or ensemble elements, it does not guarantee full cleaning or decontamination for the removal of all contaminants. The use of the term PER reduces the possible inference that gross decontamination might be the only activity needed to render clothing safe for reuse and free from contamination. In hazmat operations, the types of protective clothing might be better designed to resist contamination and allow for easily cleaning, given the clothing design and materials. This is not necessarily the case for structural or proximity firefighting protective clothing, particularly after exposure to products of combustion.
PER is an essential first step in minimizing cross-contamination preceding cleaning of ensembles or ensemble elements. PER is not considered by itself to be cleaning or decontamination of ensembles or ensemble elements. Rather, it is intended to provide a means for helping to reduce the exposure of firefighters to soils and contaminants that arise from exposures occurring during structural or proximity fires or other emergency response events. PER is also required to aid in minimizing the transfer of soils and contaminants from the emergency scene to the apparatus, station and personal vehicles. Other forms of cleaning, such as advanced or specialized cleaning, are required to provide full cleaning of the ensemble or ensemble elements.
NFPA 1851 defines two forms of PER: dry mitigation and wet mitigation. The specific provisions within the standard that address the respective techniques include the following steps:
- Firefighters carry out PER immediately after exiting the emergency scene at any incident where their protective ensemble or ensemble elements could have become soiled or contaminated.
- Upon exiting the emergency scene, the firefighter remains on SCBA air or switches to ambient air if the cylinder is empty. The purpose of remaining on air is to minimize exposure to products of combustion that may off-gas from the ensemble or ensemble elements following contaminant exposure during a structural fire and to avoid breathing in any particulates that may be dislodged from the ensemble or ensemble elements during dry mitigation.
- If returning to the emergency scene after an air cylinder change, any dry debris is brushed off the helmet, facepiece and SCBA prior to changing out the cylinder.
- If the firefighter is completing their time on scene, dry or wet mitigation techniques are conducted prior to the removal of any ensemble or ensemble elements, including the SCBA.
- The dry mitigation technique is performed by brushing debris from exterior of ensembles and ensemble elements with a soft bristle brush prior to removal.
- The wet mitigation technique is performed by gently rinsing the exterior of ensembles and ensemble elements using low-pressure and low-volume flow water. A mild detergent is recommended to aid in the wet mitigation technique followed by gentle rinsing. Heavy scrubbing or spraying with high-velocity water jets such as a power-washer must not be used.
- If used in combination, dry mitigation precedes wet mitigation.
- Following dry or wet mitigation, ensemble or ensemble elements are isolated and bagged. Where possible, ensemble or ensemble elements, even when bagged, are not transported in the passenger areas of apparatus or personal vehicles.
- Following PER, the ensemble elements are subject to the appropriate cleaning and decontamination procedures. Note: During preliminary exposure reduction, the use of a brush or any other abrasive cleaning devices on radiant reflective over shells and other components of proximity firefighter protective ensemble elements is not permitted in order to avoid compromising the proximity shell.
Dry mitigation vs. wet mitigation
The decision between dry and wet mitigation will depend on the resources available to the organization and the conditions at the emergency scene or other location.
Work by the Illinois Fire Service Institute (IFSI) under an Assistance to Firefighters Grant – as published in the Journal of Occupational and Environmental Hygiene – showed that wet mitigation techniques were more effective in removing surface contamination as compared to dry mitigation techniques. Wet mitigation techniques remove a significant amount of surface products of combustion, whereas dry mitigation techniques only remove a portion of this contamination. Techniques involving blowing air onto ensembles or ensemble elements, such as from a leaf blower, have very low effectiveness and may only redistribute contamination at the emergency scene and create inhalation hazards for unprotected personnel, and thus should be avoided.
A variety of approaches can be undertaken for applying PER techniques. Dry mitigation techniques are best achieved with a soft bristle brush, starting at the top of the firefighter’s ensemble and working downward. One method for performing wet mitigation is to use a reducer from the apparatus pump panel to supply a small hoseline, such as a forestry hose or garden hose with an adjustable nozzle, at low pressure and volume. Caution should be applied when using ordinary fire hoses and nozzles for this technique where the lowest possible flow rate is used. Most departments have a booster line or trash line that is usually three-quarters-inch or 1 inch in diameter that can be applied at a low pressure (less than 30 psi). Some departments have also used portable decontamination showers.
The process of wet mitigation should start at the top of the ensemble and rinse downward. Where necessary, a soft bristle brush may be used to gently scrub the ensemble or ensemble elements during the wet mitigation technique. The important aspects for this technique are that the spray be light, not soak through the clothing, and be able to be applied over the entire firefighter since the purpose of this mitigation technique is to primarily remove surface contamination. Wet mitigation techniques cannot remove interior layer soiling or contamination.
It is further recommended that a mild detergent be used as an aid in wet mitigation where the surfactant in the detergent is helpful for removing exterior soils. Where a mild detergent is used, it should be followed by gentle rinsing of the ensemble.
A new way to view PER
In November 2019, Fairfax County (Virginia) Fire and Rescue (FCFRD) and the NFPA FPRF conducted initial testing to assess the ability of wet PER techniques to remove surface contamination from SCBA. This work was conducted as part of a Department of Homeland Security grant that supports the research on different fire service PPE contamination and cleaning approaches.
In its initial evaluation, with support from Intertek (a leading global PPE testing and certification company), a fluorescent surrogate contamination agent was used to determine how well PER removed the contamination from both the SCBA and other parts of the PPE. Relatively simple equipment and procedures that included:
- Firefighters wore their full ensemble with SCBA (while on air) and were subjected to a spray of a non-toxic, fluorescent aerosol (GloGerm MIST) to simulate fireground exposures to heavy particulate smoke.
- The firefighters then went through PER involving an initial rinse with a handline, light scrubbing with a soapy water (using a dish washing soap-based solution) and a final rinse.
- A bank of fluorescent (UV) lights was used to view and photograph the outfitted firefighters before and after PER to determine the any areas with fluorescence that was present indicating the specific areas of the SCBA that remained contaminated following PER.
- An iterative process was followed by trying different types of brushes and rinsing techniques to find the most effective methods for removing all signs of residual contamination.
Based on this testing, it was found that certain areas of both the SCBA and other PPE showed fluorescence under UV light, which indicated the need for further attention during the wet-down and scrubbing techniques. For example, relatively stiff bristle brushes worked well on the textile strap and harness components but were less effective on hard surfaces. It was also learned that some parts of the ensemble were typically missed for removing surface contamination, such as the underside of the SCBA facepiece and palm side of gloves. The testing further allowed the research team to map out the areas where contamination would typically remain.
Through successive trials, improved results were obtained with little to no apparent remaining surrogate contamination on the PPE.
Testing demonstrates PER value
The testing also proved to be both an effective training tool for demonstrating the value and completeness for PER. Any fire department can set up similar testing for a minimal investment to demonstrate the value of PER to its members.
The following items are needed to be able to perform this testing:
- Bottles of a fluorescent liquid agent, such as GloGerm MIST (not the gel or oil). One 8-ounce bottle can provide coverage for approximately two firefighters depending on the spraying time and spray delivery rate.
- A paint sprayer or similar device that deliver the undiluted fluorescent liquid agent in a very fine mist – the finer the better. A compressed air source will also be needed to support the spraying process.
- Fluorescent UV (black) lights. Viewing is best performed with multiple 18- or 24-inch-long tube bulbs mounted vertically in custom made wooden stands that will illuminate the fully outfitted firefighter.
- Supplies for performing preliminary exposure reduction that include a handline, connected to a low water source with an appropriate spray nozzle, a set of different bristle brushes, a bucket for creating a soapy solution with a mild liquid dishwashing soap, and an area to control runoff.
Typically, the firefighter, in a standing position with arms slightly way from their bodies, should be sprayed both from the front and the back over approximately 10 seconds, starting at the top and working down. Some trial and error is necessary to determine the amount of spraying needed to replicate fireground contamination. This is best accomplished under black light conditions to see the area of coverage during the spraying process.
Further PER investigation ahead
FCFRD and the FPRF plan to use the information to perform more sophisticated measurements of contamination levels and removal rates for SCBA. Future work will involve assessing SCBA exposure occurring as the result of use in live burns. The research team will use a combination of different sampling methods to determine both gross levels of decontamination as well as target specific contaminants on SCBA both before and after burn building exposures and after various forms of cleaning. The research team intends to further investigate the contamination removal rates for PER, and then examine different types of advanced cleaning that is both manual with different detergents in addition to the use of new decontamination washing machine technology, recently made available within the department.
The views of the author do not necessarily reflect those of the sponsor.