Impact of select PPE design elements and repeated laundering in firefighter protection from smoke exposure

Human exposure to polycyclic aromatic hydrocarbons during structure fires: Concentrations outside and inside self-contained breathing apparatus and in vitro respiratory toxicity

Structure fires release several health-hazardous compounds, including polycyclic aromatic hydrocarbons (PAHs), and the use of self-contained breathing apparatus (SCBA) is mandatory to protect firefighters' airways. The characterization of PAHs released during structure fires is scarce, principally in European countries. This work elucidates the mechanisms of toxic effects associated with human exposure to PAHs released during structure fires, by assessing for the first time, the levels in the breathable air of sapper firefighters with and without the use of SCBA. An in vitro co-culture model of air-blood barrier was used to evaluate respiratory toxicity. Concentrations of total PAHs (∑PAHs) inside the burning structure were 8.20-19.8 times higher than the values monitored inside fire stations (11.5-28.0 μg/m3versus 1.41 μg/m3; p < 0.005) and 2688-5872 times higher than the levels detected inside the SCBA used during the fire events. Levels of carcinogenic PAHs were 6.90-20.5 times higher than observed for the control group (p ≤ 0.005). Inside to outside ratios (<1) suggested the contribution of PAHs from fires to the levels detected inside the protection system. Exposure to fire emissions increased the risk of lung cancer. The use of SCBA system substantially reduced exposure to PAHs, still levels detected outside/inside the SCBA facemask significantly reduced the viability of alveolar and bronchial cell lines (<70 %). Benzo(a)pyrene (100 %), naphthalene and phenanthrene (97.5 %), benzo(b+j)fluoranthene (90 %), and fluorene (87.5 %) found inside the SCBA mask were able to permeate the co-culture model of air-blood barrier. More studies need to corroborate these preliminary findings and evaluate the synergic effect of fire effluent complex mixtures and their contribution to respiratory toxicity.

Addressing the need for individual-level exposure monitoring for firefighters using silicone samplers

BACKGROUND

Firefighters are occupationally exposed to hazardous chemical mixtures. Silicone passive sampling devices capture unique exposures over time with minimal impact to the participant and allow for the analysis of a broad chemical space.

OBJECTIVE

Silicone dog tags were worn by firefighters while on- and off-duty to measure individual exposures, identify potential occupational exposures, and assess their relation to occupational variables including fire response frequency, rank, and years as a firefighter.

METHODS

Fifty-six firefighters were recruited from two fire departments with relatively high and low call volumes in the Kansas City metropolitan area to wear two different silicone dog tags as passive samplers while on- and off-duty. Each dog tag was worn for a cumulative 30-day exposure period. Extracts of the dog tags were analyzed with gas chromatography, mass spectrometry methods for 43 flame retardants (FRs), 21 volatile organic compounds (VOCs), 42 polychlorinated biphenyls (PCBs), and 63 polycyclic aromatic hydrocarbons (PAHs).

RESULTS

Ninety-two total chemicals were detected, with eight chemicals not previously reported in firefighter exposure studies. Based on the magnitude and frequency of increased exposure in on-duty dog tags, relative to paired off-duty dog tags, five PBDEs and sec-butylbenzene were identified as potential occupational exposures; sec-butylbenzene and PBDE 49 have not previously been reported in firefighter exposure studies to the authors' knowledge. Multivariate analyses for these six compounds indicated that firefighter rank, fire response rates, and years in the fire service were poor indicators of increased occupational exposure. The greatest on-duty exposures to PBDEs were found in the low-call volume department among operational firefighters. Dog tags from firefighters at the high-call volume department accounted for 75% of PCB detections; one particular fire response may have contributed to this. Additionally, there was measurable similarity in total chemical exposure profiles between paired on- and off-duty tags for some firefighters.

IMPACT

This study used personal silicone passive samplers in the configuration of dog tags worn around the neck to quantify firefighter occupational exposure in on-duty samples relative to paired off-duty samples for several chemical categories: flame retardants, VOCs, and PCBs. Five PBDEs and sec-butylbenzene were identified as potential occupational exposures, however their prevalence in on-duty tags was not associated with frequency of fire responses, firefighter rank, or years the firefighter has been in the fire service. Additionally, similarity between chemical exposures in on- and off-duty tags from the same firefighter invites further investigation into individual behaviors influencing occupational and para-occupational exposures.

Evaluating the ingress of total polycyclic aromatic hydrocarbons (PAHs) specifically naphthalene through firefighter hoods and base layers

Structural firefighters are exposed to an array of polycyclic aromatic hydrocarbons (PAHs) as a result of incomplete combustion of both synthetic and natural materials. PAHs are found in both the particulate and vapor phases in the firefighting environment and are significantly associated with acute and chronic diseases, including cancer. Using a fireground exposure simulator (FES) and standing mannequins dressed in four different firefighter personal protective equipment (PPE) conditions, each with varying levels of protective hood interface and particulate-blocking features, the efficacy of the hoods was assessed against the ingress of PAHs (specifically, naphthalene). The authors also explored the effectiveness of a 100% cotton turtleneck at further attenuating the amount of naphthalene reaching the surface of the mannequin's neck. Air samples were collected at the breathing zone, abdomen, and thigh heights from the 6 ft-2 in mannequins used in this study. Naphthalene was the most abundant PAH (55% of the total PAH concentrations) in the FES and existed primarily in the vapor phase (92% vapor in the breathing zone). Additionally, bulk base layer and under the base layer polytetrafluoroethylene (PTFE) filter samples (used as skin surrogates) were collected from the neck region of the mannequins and analyzed for PAHs. A larger percentage of naphthalene was collected on the filter under the traditional knit hoods than on the cotton base layer, suggesting a small protective effect of the base layer against solid-phase naphthalene. Previous studies investigating naphthalene by employing air sampling under PPE have found a larger protective effect of base layers against the ingress of naphthalene vapor. PAHs that exist primarily as particulate in the fire environment were largely not detected on the base layers or PTFE filters under the gear. Further research is needed that involves more sensitive methods and non-static human subjects.

Air, Skin, and Biological Monitoring of French Fire Instructors' Exposure to Particles/PAHs During Controlled Fire and Mitigation Strategies

Occupational exposure as a firefighter was recently classified as carcinogenic to humans by the IARC. Fire instructors' exposure to carcinogenic PAHs is a major concern, and studies that have tried to assess the determinants of their exposure are scarce. An air and biomonitoring study was conducted in fire instructors performing simulated training exercises in enclosed containers. Air samples were collected, as well as urine samples from 22 firefighting instructors, and skin wipes were collected from FFs' skin at the end of the exercises. PAH metabolites (1-hydroxypyrene, 3-hydroxybenzo(a)pyrene, 2/3-hydroxyfluorene, and 2/3-hydroxyphenanthrene) were measured in urine samples at three sampling times (beginning of shift, end of shift, and next morning). Airborne PAHs were dominated by low molecular weight compounds (naphthalene), and levels were as high as 67 µg·m-3 close to the containers, decreasing at higher distances. Skin contamination was observed both on the neck/face and hands/wrists of fire instructors and pilots. Ten times lower skin contamination was observed when nitrile undergloves were worn. High internal exposure was measured, with 1-hydroxypyrene and 3-hydroxybenzo(a)pyrene levels frequently exceeding maximum recommended values in occupational settings (up to 2.8 µmol/mol creatinine for 1-OHP, 14 µmol/mol creatinine for ΣOH-PAH, and 1.0 nmol/mol creatinine for 3-OHBaP), whereas benzene exposure was revealed to be very low. These types of exposure were found to derive both from dermal absorption (combustion products deposited on the skin) and inhalation (when removing SCBA outside the containers). Several recommendations are proposed in order to reduce both exposure routes (nitrile undergloves and half-masks in the vicinity of containers), harmonise decontamination (PPEs) and cleaning procedures, and prevent the dermal absorption of PAH from turnout gear. This study emphasises the complex PAH exposure profiles of fire instructors and characterises the main drivers of exposure, highlighting the need for better mitigation strategies.

The role of personal protective equipment (PPE) in reducing firefighter exposure to chemical hazards: A systematic review

This paper aims to investigate the effectiveness of personal protective equipment (PPE) in reducing firefighter exposure to various hazardous chemicals from the smoke emitted during fires. A systematic review of peer-reviewed articles was undertaken utilizing five databases: Medline, Embase, Web of Science, Scopus, and CINHAL. Studies published between 2013 and 2023 that investigated the effectiveness of PPE in reducing firsthand exposure to at least one chemical were included. Extracted data were grouped into two overarching themes related to PPE: (a) Respiratory Protection and (b) Personal Protective Clothing (PPC). Overall, 21 studies met the inclusion criteria and were considered for further analysis. Respiratory protection, particularly self-contained breathing apparatus (SCBA), offered the most protection in preventing inhalation exposure to chemical hazards. There was limited evidence on the effectiveness of firefighter turnout gear in reducing skin contamination. Combustion contaminants, especially highly volatile compounds like benzene, were found to permeate and penetrate through and around the protective clothing. In conclusion, certain respirators, particularly SCBA, provided the best protection against inhalation exposure to chemicals; however, PPC did not appear to provide complete protection, particularly against the more volatile chemicals like benzene.

The Emission Characteristics and Health Risks of Firefighter-Accessed Fire: A Review

The exacerbation of wildfires caused by global warming poses a significant threat to human health and environmental integrity. This review examines the particulate matter (PM) and gaseous pollutants resulting from fire incidents and their impacts on individual health, with a specific focus on the occupational hazards faced by firefighters. Of particular concern is the release of carbon-containing gases and fine particulate matter (PM2.5) from forest fires and urban conflagrations, which exceed the recommended limits and pose severe health risks. Firefighters exposed to these pollutants demonstrate an elevated risk of developing pulmonary and cardiovascular diseases and cancer compared to the general population, indicating an urgent need for enhanced protective measures and health management strategies for firefighters. Through a meticulous analysis of the current research findings, this review delineates future research directions, focusing on the composition and properties of these pollutants, the impacts of fire-emitted pollutants on human health, and the development of novel protective technologies.

Breast Cancer-Related Chemical Exposures in Firefighters

To fill a research gap on firefighter exposures and breast cancer risk, and guide exposure reduction, we aimed to identify firefighter occupational exposures linked to breast cancer. We conducted a systematic search and review to identify firefighter chemical exposures and then identified the subset that was associated with breast cancer. To do this, we compared the firefighter exposures with chemicals that have been shown to increase breast cancer risk in epidemiological studies or increase mammary gland tumors in experimental toxicology studies. For each exposure, we assigned a strength of evidence for the association with firefighter occupation and for the association with breast cancer risk. We identified twelve chemicals or chemical groups that were both linked to breast cancer and were firefighter occupational exposures, including polycyclic aromatic hydrocarbons, volatile aromatics, per- and polyfluoroalkyl substances, persistent organohalogens, and halogenated organophosphate flame retardants. Many of these were found at elevated levels in firefighting environments and were statistically significantly higher in firefighters after firefighting or when compared to the general population. Common exposure sources included combustion byproducts, diesel fuel and exhaust, firefighting foams, and flame retardants. Our findings highlight breast-cancer-related chemical exposures in the firefighting profession to guide equitable worker's compensation policies and exposure reduction.

Evaluating workplace protection factors (WPFs) of different firefighter PPE interface control measures for select volatile organic compounds (VOCs)

Structural firefighters are exposed to a complex set of contaminants and combustion byproducts, including volatile organic compounds (VOCs). Additionally, recent studies have found structural firefighters' skin may be exposed to multiple chemical compounds via permeation or penetration of chemical byproducts through or around personal protective equipment (PPE). This mannequin-based study evaluated the effectiveness of four different PPE conditions with varying contamination control measures (incorporating PPE interface design features and particulate blocking materials) to protect against ingress of several VOCs in a smoke exposure chamber. We also investigated the effectiveness of long-sleeve base layer clothing to provide additional protection against skin contamination. Outside gear air concentrations were measured from within the smoke exposure chamber at the breathing zone, abdomen, and thigh heights. Personal air concentrations were collected from mannequins under PPE at the same general heights and under the base layer at abdomen and thigh heights. Sampled contaminants included benzene, toluene, styrene, and naphthalene. Results suggest that VOCs can readily penetrate the ensembles. Workplace protection factors (WPFs) were near one for benzene and toluene and increased with increasing molecular weight of the contaminants. WPFs were generally lower under hoods and jackets compared to under pants. For all PPE conditions, the pants appeared to provide the greatest overall protection against ingress of VOCs, but this may be due in part to the lower air concentrations toward the floor (and cuffs of pants) relative to the thigh-height outside gear concentrations used in calculating the WPFs. Providing added interface control measures and adding particulate-blocking materials appeared to provide a protective benefit against less-volatile chemicals, like naphthalene and styrene.

Use of silicone wristbands to measure firefighters' exposures to polycyclic aromatic hydrocarbons (PAHs) during live fire training

Firefighters experience exposures to carcinogenic and mutagenic substances, including polycyclic aromatic hydrocarbons (PAHs). Silicone wristbands (SWBs) have been used as passive samplers to assess firefighters' exposures over the course of a shift but their utility in measuring short term exposures, source of exposure, and correlations with other measurements of exposure have not yet been investigated. In this study, SWBs were used to measure the concentrations of 16 priority PAHs inside and outside of firefighters' personal protective equipment (PPE) while firefighting. SWBs were placed on the wrist and jacket of 20 firefighters conducting live fire training. Correlations were made with matching data from a sister project that measured urinary concentrations of PAH metabolites and PAH concentrations from personal air samples from the same participants. Naphthalene, acenaphthylene and phenanthrene had the highest geometric mean concentrations in both jacket and wrist SWB, with 1040, 320, 180 ng/g SWB for jacket and 55.0, 4.9, and 6.0 ng/g SWB for wrist, respectively. Ratios of concentrations between the jacket and wrist SWBs were calculated as worker protection factors (WPFs) and averaged 40.1 for total PAHs and ranged from 2.8 to 214 for individual PAHs, similar to previous studies. Several significant correlations were observed between PAHs in jacket SWBs and air samples (e.g., total and low molecular weight PAHs, r = 0.55 and 0.59, p < 0.05, respectively). A few correlations were found between PAHs from SWBs worn on the wrist and jacket, and urinary concentrations of PAH metabolites and PAH concentrations in air samples. The ability of the SWBs to accurately capture exposures to various PAHs was likely influenced by short sampling time, high temperatures, and high turbulence. Future work should further examine the limitations of SWBs for PAH exposures in firefighting, and other extreme environments.

Evaluating the performance of surfactant and charcoal-based cleaning products to effectively remove PAHs from firefighter gear

Firefighters regularly respond to fire scenes where a mixture of chemicals including volatile, semi-volatile, and nonvolatile compounds are present in smoke and soot. Polycyclic aromatic hydrocarbons (PAHs) are common contaminants at fire scenes that may be deposited on the gear and the individual firefighter. Laundering is a common approach for the decontamination of contaminated gear. Surfactants are widely used by firefighters during laundering to remove PAHs as they are generally non-toxic and biodegradable. The removal of PAHs depends on the surfactant types, chemistries, and concentrations. This study evaluated the effect of surfactant concentrations to remove persistent contaminants like PAHs from turnout gear. The cleaning performance of different types of surfactants was also evaluated. Outer shell fabrics were contaminated with a standard mixture of 16 PAH compounds, and two commercial detergents were used at different concentrations. Additionally, the cleaning efficacy of eight commercially available regular and charcoal-based cleaning products was also determined against PAHs at a single surfactant concentration. For the decontamination method, a bench-scale washing procedure simulating the National Fire Protection Assocation 1851 laundering process was used. The removal efficacy of high molecular weight (HMW) PAHs were found to be lower compared to the low molecular weight PAHs for any type or any concentration of detergent. Our research also showed that the recommended surfactant concentrations provided by detergent manufacturers can be ineffective at removing the HMW PAHs from heavily contaminated fabric. With 1mL of detergent in a 100-mL bath, which is multiple times higher than recommended amount, only 40% of HMW PAHs were removed. The cleaning efficacy can be increased to above 90% by using higher concentrations of detergents. This research shows that firefighters may need to use a higher concentration of detergent than the recommended amount to effectively remove PAHs from the gear. All the regular and charcoal-based detergents were able to remove PAHs effectively from contaminated fabrics when a higher concentration of detergent was used.

Silicone passive sampling used to identify novel dermal chemical exposures of firefighters and assess PPE innovations

A plethora of chemicals are released into the air during combustion events, including a class of compounds called polycyclic aromatic hydrocarbons (PAHs). PAHs have been implicated in increased risk of cancer and cardiovascular disease, both of which are disease endpoints of concern in structural firefighters. Current commercially available personal protective equipment (PPE) typically worn by structural firefighters during fire responses have gaps in interfaces between the ensemble elements (e.g., hood and jacket) that allow for ingress of contaminants and dermal exposure. This pilot study aims to use silicone passive sampling to assess improvements in dermal protection afforded by a novel configuration of PPE, which incorporates a one-piece liner to eliminate gaps in two critical interfaces between pieces of gear. The study compared protection against parent and alkylated PAHs between the one-piece liner PPE and the standard configuration of PPE with traditional firefighting jacket and pants. Mannequins (n = 16) dressed in the PPE ensembles were placed in a Fireground Exposure Simulator for 10 min, and exposed to smoke from a combusting couch. Silicone passive samplers were placed underneath PPE at vulnerable locations near interfaces in standard PPE, and in the chamber air, to measure PAHs and calculate the dermal protection provided by both types of PPE. Silicone passive sampling methodology and analyses using gas chromatography with mass-spectrometry proved to be well-suited for this intervention study, allowing for the calculation and comparison of worker protection factors for 51 detected PAHs. Paired comparisons of the two PPE configurations found greater sum 2-3 ring PAH exposure underneath the standard PPE than the intervention PPE at the neck and chest, and at the chest for 4-7 ring PAHs (respective p-values: 0.00113, 0.0145, and 0.0196). Mean worker protection factors of the intervention PPE were also greater than the standard PPE for 98% of PAHs at the neck and chest. Notably, the intervention PPE showed more than 30 times the protection compared to the standard PPE against two highly carcinogenic PAHs, dibenzo[a,l]pyrene and benzo[c]fluorene. Nine of the detected PAHs in this study have not been previously reported in fireground exposure studies, and 26 other chemicals (not PAHs) were detected using a large chemical screening method on a subset of the silicone samplers. Silicone passive sampling appears to be an effective means for measuring dermal exposure reduction to fireground smoke, providing evidence in this study that reducing gaps in PPE interfaces could be further pursued as an intervention to reduce dermal exposure to PAHs, among other chemicals.

Use of Preliminary Exposure Reduction Practices or Laundering to Mitigate Polycyclic Aromatic Hydrocarbon Contamination on Firefighter Personal Protective Equipment Ensembles

Chronic health risks associated with firefighting continue to be documented and studied, however, the complexity of occupational exposures and the relationship between occupational exposure and contaminated personal protective equipment (PPE) remains unknown. Recent work has revealed that common PPE cleaning practices, which are becoming increasingly more common in the fire service, are not effective in removing certain contaminants, such as polycyclic aromatic hydrocarbons (PAHs), from PPE. To better understand the relationship between contaminated firefighter PPE and potential exposure to PAHs, and to gain further understanding of the efficacy of cleaning practices, we used a standardized fire exposure simulator that created repeatable conditions and measured PPE surface contamination levels via wipe sampling and filters attached to firefighter gear worn by standing mannequins. This study examined the effects of repeated (40 cycles) PPE cleaning (laundering and on-scene preliminary exposure reduction (PER) techniques) and repeated exposures on PAH concentration on different surfaces. Further exploration included examination of contamination breakthrough of turnout jackets (comparing outer shell and interior liner) and evaluation of off-gassing PAHs from used gear after different cleaning treatments. When compared by jacket closure type (zipper and hook and dee), total PAH concentration wiped from gear after exposure and cleanings showed no significant differences. Regression analysis indicated that there was no effect of repeated exposures on PAH contamination levels (all sampling sites combined; before fire 10, 20, and 40; after fire 1, 10, 20, and 40; p-value > 0.05). Both laundering and on-scene PER significantly reduced contamination levels on the exterior pants and helmets and were effective at reducing PAH contamination. The jacket outer shell had significantly higher PAH contamination than the jacket liner. Both laundering and wet soap PER methods (post-fire) are effective in reducing surface contamination and appear to prevent accumulation of contamination after repeated exposures. Semi-volatile PAHs deep within the fibers of bulky PPE are not effectively reduced via PER or machine laundering, therefore, permitting continued off-gassing of these compounds. Further research is needed to identify the most effective laundering methods for firefighter turnout gear that considers the broad spectrum of common contaminants.

Contamination of UK firefighters personal protective equipment and workplaces

Firefighters' personal protective equipment (PPE) is a potential source of chronic exposure to toxic contaminants commonly released from fires. These contaminants have also been found in fire stations. However, little research characterises the routes via which fire contaminants travel back to fire stations. The UK Firefighter Contamination Survey provides information on firefighters' PPE provision, decontamination, and storage practices. All serving UK firefighters were eligible to take part in the survey, which comprised 64 questions. A total of 10,649 responses were included for analysis, accounting for roughly 24% of the UK's firefighting workforce. Results revealed that most firefighters (84%) de-robe contaminated PPE/workwear after re-entering the appliance cab. There was a significant decreasing tendency to send PPE for cleaning after every incident with increasing seniority of role, length of service, and fire attendance frequency. Around one third of firefighters cleaned PPE after every incident. A number of issues were linked to external professional cleaning services, e.g. shrinkage, fit, turn-around time, and stock of reserve/pooled PPE. PPE storage was found to be a potential source of cross contamination, with almost half of firefighters (45%) indicating clean and dirty PPE is not stored separately. More than half of firefighters (57%) stored fire gloves (an item sent for professional decontamination by only 19% of firefighters, and never cleaned by 20%) within other items of PPE such as helmets, boots and tunic/trouser pockets. The survey's results can be used to target gaps in decontamination measures within UK Fire and Rescue Services.

Exposure Risks and Potential Control Measures for a Fire Behavior Lab Training Structure: Part B. Chemical Gas Concentrations

Firefighters' or instructors' exposure to airborne chemicals during live-fire training may depend on fuels being burned, fuel orientation and participants' location within the structure. This study was designed to evaluate the impact of different control measures on exposure risk to combustion byproducts during fire dynamics training where fuel packages are mounted at or near the ceiling. These measures included substitution of training fuels (low density wood fiberboard, oriented strand board (OSB), pallets, particle board, plywood) and adoption of engineering controls such as changing the location of the instructor and students using the structure. Experiments were conducted for two different training durations: the typical six ventilation cycle (6-cycle) and a shorter three ventilation cycle (3-cycle) with a subset of training fuels. In Part A of this series, we characterized the fire dynamics within the structure, including the ability of each fuel to provide an environment that achieves the training objectives. Here, in Part B, airborne chemical concentrations are reported at the location where fire instructors would typically be operating. We hypothesized that utilizing a training fuel package with solid wood pallets would result in lower concentrations of airborne contaminants at the rear instructor location than wood-based sheet products containing additional resins and/or waxes. In the 6-cycle experiments (at the rear instructor location), OSB-fueled fires produced the highest median concentrations of benzene and 1,3 butadiene, plywood-fueled fires produced the highest total polycyclic aromatic hydrocarbon (PAH) concentrations, particle board-fueled fires produced the highest methyl isocyanate concentrations, and pallet-fueled fires produced the highest hydrogen chloride concentrations. All fuels other than particle board produced similarly high levels of formaldehyde at the rear instructor location. The OSB fuel package created the most consistent fire dynamics over 6-cycles, while fiberboard resulted in consistent fire dynamics only for the first three cycles. In the follow-on 3-cycle experiment, PAH, benzene, and aldehyde concentrations were similar for the OSB and fiberboard-fueled fires. Air sampling did not identify any clear differences between training fires from burning solid wood pallets and those that incorporate wood-based sheet products for this commonly employed fuel arrangement with fuels mounted high in the compartment. However, it was found that exposure can be reduced by moving firefighters and instructors lower in the compartment and/or by moving the instructor in charge of ventilation from the rear of the structure (where highest concentrations were consistently measured) to an outside position.

Exposure to PAHs during Firefighting Activities: A Review on Skin Levels, In Vitro/In Vivo Bioavailability, and Health Risks

Occupational exposure as a firefighter is a complex activity that continuously exposes subjects to several health hazards including fire emissions during firefighting. Firefighters are exposed to polycyclic aromatic hydrocarbons (PAHs), known as toxic, mutagenic, and carcinogenic compounds, by inhalation, dermal contact, and ingestion. In this work, a literature overview of firefighters' dermal exposure to PAHs after firefighting and data retrieved from skin in vitro/in vivo studies related to their dermal absorption, bioavailability, and associated toxicological and carcinogenic effects are reviewed. The evidence demonstrates the contamination of firefighters' skin with PAHs, mainly on the neck (2.23-62.50 ng/cm²), wrists (0.37-8.30 ng/cm²), face (2.50-4.82 ng/cm²), and hands (1.59-4.69 ng/cm²). Concentrations of possible/probable carcinogens (0.82-33.69 ng/cm²), including benzopyrene isomers, were found on firefighters' skin. PAHs penetrate the skin tissues, even at low concentrations, by absorption and/or diffusion, and are locally metabolized and distributed by the blood route to other tissues/organs. Lighter PAHs presented increased dermal permeabilities and absorption rates than heavier compounds. Topical PAHs activate the aryl hydrocarbon receptor and promote the enzymatic generation of reactive intermediates that may cause protein and/or DNA adducts. Future research should include in vitro/in vivo assays to perform a more realistic health risk assessment and to explore the contribution of dermal exposure to PAHs total internal dose.

Hierarchy of contamination control in the fire service: Review of exposure control options to reduce cancer risk

The international fire service community is actively engaged in a wide range of activities focused on development, testing, and implementation of effective approaches to reduce exposure to contaminants and the related cancer risk. However, these activities are often viewed independent of each other and in the absence of the larger overall effort of occupational health risk mitigation. This narrative review synthesizes the current research on fire service contamination control in the context of the National Institute for Occupational Safety and Health (NIOSH) Hierarchy of Controls, a framework that supports decision making around implementing feasible and effective control solutions in occupational settings. Using this approach, we identify evidence-based measures that have been investigated and that can be implemented to protect firefighters during an emergency response, in the fire apparatus and at the fire station, and identify several knowledge gaps that remain. While a great deal of research and development has been focused on improving personal protective equipment for the various risks faced by the fire service, these measures are considered less effective. Administrative and engineering controls that can be used during and after the firefight have also received increased research interest in recent years. However, less research and development have been focused on higher level control measures such as engineering, substitution, and elimination, which may be the most effective, but are challenging to implement. A comprehensive approach that considers each level of control and how it can be implemented, and that is mindful of the need to balance contamination risk reduction against the fire service mission to save lives and protect property, is likely to be the most effective.

White Light-Photolysis for the Removal of Polycyclic Aromatic Hydrocarbons from Proximity Firefighting Protective Clothing

The presence of polycyclic aromatic hydrocarbons (PAHs) on firefighters' personal protective equipment is a concern. One form of preventing from these compounds is to decontaminate proximity firefighting protective clothing (PFPC). Traditional decontamination methods do not promote total removal of pollutants and alter the properties of PFPC. The objective of this work was to evaluate the effectiveness of white light-photolysis (WLP), an advanced oxidation process (AOP), for removing PAHs from PFPC, while maintaining the integrity of the fabric fibers. Experiments were carried out, varying reaction time and concentration of H₂O₂. With WLP (without H₂O₂), it was possible to remove more than 73% of the PAHs tested from the outer layer of PFPC in 3 days. The WLP provided the greatest removal of PAHs, compared with the most common mechanical decontamination techniques (laundering and wet-soap brushing). The fibers' integrity after exposure to the white light was evaluated with infrared spectroscopy and scanning electron microscopy/energy dispersive X-ray spectrometry. In addition, a tearing strength test was performed. No remarkable fabric degradation was observed, indicating a possible, routine-compatible, simple, and inexpensive method of decontamination of PFPC, based on photolysis, which is effective in the degradation of PAHs and maintains the integrity of fabric fibers.

Firefighters' urinary concentrations of VOC metabolites after controlled-residential and training fire responses

INTRODUCTION

Firefighters are exposed to volatile organic compounds (VOCs) during structural fire responses and training fires, several of which (e.g., benzene, acrolein, styrene) are known or probable carcinogens. Exposure studies have found that firefighters can absorb chemicals like benzene even when self-contained breathing apparatus (SCBA) are worn, suggesting that dermal absorption contributes to potentially harmful exposures. However, few studies have characterized VOC metabolites in urine from firefighters.

OBJECTIVES

We quantified VOC metabolites in firefighters' urine following live firefighting activity across two field studies.

METHODS

In two separate controlled field studies, spot urine was collected before and 3 h after firefighters and firefighter students responded to simulated residential and training fires. Urine was also collected from instructors from the training fire study before the first and 3 h after the last training scenario for each day (instructors led three training scenarios per day). Samples were analyzed for metabolites of VOCs to which firefighters may be exposed.

RESULTS

In the residential fire study, urinary metabolites of xylenes (2MHA), toluene (BzMA), and styrene (MADA) increased significantly (at 0.05 level) from pre- to post-fire. In the training fire study, MADA concentrations increased significantly from pre- to post-fire for both firefighter students and instructors. Urinary concentrations of benzene metabolites (MUCA and PhMA) increased significantly from pre- to post-fire for instructors, while metabolites of xylenes (3MHA+4MHA) and acrolein (3HPMA) increased significantly for firefighter students. The two highest MUCA concentrations measured post-shift from instructors exceeded the BEI of 500 μg/g creatinine.

CONCLUSIONS

Some of the metabolites that were significantly elevated post-fire are known or probable human carcinogens (benzene, styrene, acrolein); thus, exposure to these compounds should be eliminated or reduced as much as possible through the hierarchy of controls. Given stringent use of SCBA, it appears that dermal exposure contributes in part to the levels measured here.

Characterizing exposure to benzene, toluene, and naphthalene in firefighters wearing different types of new or laundered PPE

The fire service has become more aware of the potential for adverse health outcomes due to occupational exposure to hazardous combustion byproducts. Because of these concerns, personal protective equipment (PPE) manufacturers have developed new protection concepts like particulate-blocking hoods to reduce firefighters' exposures. Additionally, fire departments have implemented exposure reduction interventions like routine laundering of PPE after fire responses. This study utilized a fireground exposure simulator (FES) with 24 firefighters performing firefighting activities on three consecutive days wearing one of three PPE ensembles (stratified by hood design and treatment of PPE): 1) new knit hood, new turnout jacket and new turnout pants 2) new particulate-blocking hood, new turnout jacket and new turnout pants or 3) laundered particulate-blocking hood, laundered turnout jacket and laundered turnout pants. As firefighters performed the firefighting activities, personal air sampling on the outside and inside the turnout jacket was conducted to quantify exposures to volatile organic compounds (VOCs) and naphthalene. Pre- and immediately post-fire exhaled breath samples were collected to characterize the absorption of VOCs. Benzene, toluene, and naphthalene were found to diffuse through and/or around the turnout jacket, as inside jacket benzene concentrations were often near levels reported outside the turnout jacket (9.7-11.7% median benzene reduction from outside the jacket to inside the jacket). The PPE ensemble did not appear to affect the level of contamination found inside the jacket for the compounds evaluated here. Benzene concentrations in exhaled breath increased significantly from pre to post-fire for all three groups (p-values < 0.05). The difference of pre-to post-fire benzene exhaled breath concentrations were positively associated with inside jacket and outside jacket benzene concentrations, even though self-contained breathing apparatus (SCBA) were worn during each response. This suggests the firefighters can absorb these compounds via the dermal route.

Disposition of Fluorine on New Firefighter Turnout Gear

Firefighter turnout gear is essential for reducing occupational exposure to hazardous chemicals during training and fire events. Per-and polyfluoroalkyl substances (PFASs) are observed in firefighter serum, and possible occupational sources include the air and dust of fires, aqueous film-forming foam, and turnout gear. Limited data exist for nonvolatile and volatile PFASs on firefighter turnout gear and the disposition of fluorine on the individual layers of turnout gear. Further implications for exposure to fluorine on turnout gear are not well understood. Three unused turnout garments purchased in 2019 and one purchased in 2008, were analyzed for 50 nonvolatile and 15 volatile PFASs by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-qTOF-MS) and gas chromatography-mass spectrometry (GC-MS), respectively. Particle-induced gamma ray emission (PIGE), a surface technique, and instrumental neutron activation analysis (INAA), a bulk technique, were used to measure total fluorine. Bulk characterization of the layers by pyrolysis-GC/MS (py-GC/MS) was used to differentiate fluoropolymer (e.g., PTFE) films from textile layers finished with side-chain polymers. The outer layer, moisture barrier, and thermal layers of the turnout gear all yielded measured concentrations of volatile PFASs that exceeded nonvolatile PFAS concentrations, but the summed molar concentrations made up only a small fraction of total fluorine (0.0016-6.7%). Moisture barrier layers comprised a PTFE film, as determined by py-GC-MS, and gave the highest individual nonvolatile (0.159 mg F/kg) and volatile PFAS (20.7 mg F/kg) as well as total fluorine (122,000 mg F/kg) concentrations. Outer and thermal layers comprised aromatic polyamide-based fibers (aramid) treated with side-chain fluoropolymers and had lower levels of individual nonvolatile and volatile PFASs. Equal concentrations of total fluorine by both PIGE and INAA on the outer and thermal layers is consistent with treatment with a side-chain fluoropolymer coating. New turnout gear should be examined as a potential source of firefighter occupational exposure to nonvolatile and volatile PFASs in future assessments.

Organophosphate and Organohalogen Flame-Retardant Exposure and Thyroid Hormone Disruption in a Cross-Sectional Study of Female Firefighters and Office Workers from San Francisco

Occupational exposures to flame retardants (FRs), a class of suspected endocrine-disrupting compounds, are of health concern for firefighters. We sought to characterize exposure to FR compounds and evaluate their association with thyroid hormone levels, a biomarker of early effect, in female firefighters and office workers in San Francisco. In a cross-sectional study, we measured replacement organophosphate and organohalogen FRs in spot urine samples from firefighters (N = 86) and office workers (N = 84), as well as total thyroxine (T4) and thyroid-stimulating hormone in plasma for 84 firefighters and 81 office workers. Median bis(1,3-dichloro-2-propyl)phosphate (BDCPP) levels were 5 times higher in firefighters than office workers. Among firefighters, a doubling of BDCPP was associated with a 2.88% decrease (95% confidence interval -5.28, -0.42) in T4. We did not observe significant associations between FRs and T4 among office workers. In the full group, intermediate body mass index and a college education were associated with higher FR levels. The inverse association observed between FRs and T4 coupled with the lack of studies on women workers and evidence of adverse health effects from FR exposure─including endocrine disruption and breast cancer risk─warrant further research on occupational exposures and identification of opportunities for exposure reduction.

Evaluation of an Ozone Chamber as a Routine Method to Decontaminate Firefighters' PPE

Ozone chambers have emerged as an alternative method to decontaminate firefighters' Personal Protective Equipment (PPE) from toxic fire residues. This work evaluated the efficiency of using an ozone chamber to clean firefighters' PPE. This was achieved by studying the degradation of pyrene and 9-methylanthracene polycyclic aromatic hydrocarbons (PAHs). The following experiments were performed: (i) insufflating ozone into PAH solutions (homogeneous setup), and (ii) exposing pieces of PPE impregnated with the PAHs to an ozone atmosphere for up to one hour (heterogeneous setup). The ozonolysis products were assessed by Fourier Transform Infrared Spectroscopy (FTIR), Thin-Layer Chromatography (TLC), and Mass Spectrometry (MS) analysis. In the homogeneous experiments, compounds of a higher molecular weight were produced due to the incorporation of oxygen into the PAH structures. Some of these new compounds included 4-oxapyren-5-one (m/z 220) and phenanthrene-4,5-dicarboxaldehyde (m/z 234) from pyrene; or 9-anthracenecarboxaldehyde (m/z 207) and hydroxy-9,10-anthracenedione (m/z 225) from 9-methylanthracene. In the heterogeneous experiments, a lower oxidation was revealed, since no byproducts were detected using FTIR and TLC, but only using MS. However, in both experiments, significant amounts of the original PAHs were still present even after one hour of ozone treatment. Thus, although some partial chemical degradation was observed, the remaining PAH and the new oxygenated-PAH compounds (equally or more toxic than the initial molecules) alerted us of the risks to firefighters' health when using an ozone chamber as a unique decontamination method. These results do not prove the ozone-advertised efficiency of the ozone chambers for decontaminating (degrading the toxic combustion residues into innocuous compounds) firefighters' PPE.

Effects of firefighting hood design, laundering and doffing on smoke protection, heat stress and wearability

Firefighter hoods must provide protection from elevated temperatures and products of combustion (e.g. particulate) while simultaneously being wearable (comfortable and not interfering with firefighting activities). The purpose of this study was to quantify the impact of (1) hood design (traditional knit hood vs particulate-blocking hood), (2) repeated laundering, and (3) hood removal method (traditional vs overhead doffing) on (a) protection from soot contamination on the neck, (b) heat stress and (c) wearability measures. Using a fireground exposure simulator, 24 firefighters performed firefighting activities in realistic smoke and heat conditions using a new knit hood, new particulate-blocking hood and laundered particulate-blocking hood. Overall, soot contamination levels measured from neck skin were lower when wearing the laundered particulate-blocking hoods compared to new knit hoods, and when using the overhead hood removal process. No significant differences in skin temperature, core temperature, heart rate or wearability measures were found between the hood conditions. Practitioner Summary: The addition of a particulate-blocking layer to firefighters' traditional two-ply hood was found to reduce the PAH contamination reaching the neck but did not affect heat stress measurements or thermal perceptions. Modifying the process for hood removal resulted in a larger reduction in neck skin contamination than design modification. Abbreviations: ANOVA: analysis of variance; B: new particulate-blocking hood and PPE (PPE configuration); FES: fireground exposure simulator; GI: gastrointestinal; K: new knit hood and PPE (PPE configuration); L: laundered particulate-blocking hood and PPE (PPE configuration); LOD: limit of detection; MLE: maximum likelihood estimation; NFPA: National fire protection association; PAH: polycyclic aromatic hydrocarbon; PPE: personal protective equipment; SCBA: self-contained breathing apparatus; THL: total heat loss; TPP: thermal protective performance.