Firefighters wear personal protective equipment to protect them from the thermal and chemical environment in which they operate. The self-contained breathing apparatus (SCBA) provides isolation of the airway from the hazardous fireground. National standards limit SCBA weight, however, integration of additional features could result in an SCBA exceeding the current limit. The purpose of this study was to examine the effects of increased SCBA weight on firefighters\' physiological responses, work output, dynamic stability, and comfort. Completion of simulated firefighting activities induced a strong physiological response. Peak oxygen consumption was higher with the lightest SCBA than the heaviest SCBA. Few other physiological differences were noted as SCBA weight increased. Importantly, increased SCBA weight resulted in significantly more negative perceptions by the firefighters and a trend towards significance for the duration of work time prior to reaching volitional fatigue. These results should be considered when assessing changes to existing SCBA weight limits.
Increased SCBA weight above existing national standards resulted in negative perceptions by the firefighters, but not significant physiological changes after two simulated bouts of firefighting activity. SCBA weight had a nearly significant impact on the time firefighters worked before reaching volitional fatigue, with heavier SCBA trending towards decreased working time.

This research sought to evaluate the thermal zones of the upper body and firefighter personal protective equipment (PPE) immediately following uncompensable heat stress (0.03 °C increase/min). We hypothesized that the frontal portion of the head and the inside of the firefighter helmet would be the hottest as measured by infrared thermography. This hypothesis was due to previous research demonstrating that the head accounts for ∼8-10% of the body surface area, but it accounts for ∼20% of the overall body heat dissipation during moderate exercise. Twenty participants performed a 21-min graded treadmill exercise protocol (Altered Modified Naughton) in an environmental chamber (35 °C, 50 % humidity) in firefighter PPE. The body areas analyzed were the frontal area of the head, chest, abdomen, arm, neck, upper back, and lower back. The areas of the PPE that were analyzed were the inside of the helmet and the jacket. The hottest areas of the body post-exercise were the frontal area of the head (mean: 37.3 ± 0.4 °C), chest (mean: 37.5 ± 0.3 °C), and upper back (mean: 37.3 ± 0.4 °C). The coldest area of the upper body was the abdomen (mean: 36.1 ± 0.4 °C). The peak temperature of the inside of the helmet increased (p < 0.001) by 9.8 °C from 27.7 ± 1.6 °C to 37.4 ± 0.7 °C, and the inside of the jacket increased (p < 0.001) by 7.3 °C from 29.2 ± 1.7 °C to 36.5 ± 0.4 °C. The results of this study are relevant for cooling strategies for firefighters.

Firefighters are often exposed to high temperatures and by-products of combustion, which can affect their health. In this study, we assessed the impact of acute exposure of firefighters in fire simulators. Twenty male firefighters were exposed to fire simulators, and observed in four phases: pre-exposure (group 0, control) and after the end of the first (group 1), second (group 2), and fourth (group 3) weeks of training. Blood samples were collected and dosed to evaluate the response of the immune, inflammatory (C-reactive protein, IL6, and IL10), and endocrine systems (cortisone, total testosterone, free testosterone, SHBG, bioavailable testosterone, TSH, and free T4). In groups 0, 1, and 3, a thermographic evaluation was also carried out to study the temperature and body heat flow of the participants. Regarding the inflammatory process, an increase in C-reactive protein and a reduction in IL-10 were observed. With respect to hormonal markers, an increase in cortisol and reduced levels of free T4 and bioavailable testosterone were found after exposure, with recovery of testosterone levels in the final week of training. Thermoregulatory adaptation of the organism has been associated with changes in heat flow in the organism in people subjected to extreme temperatures, with emphasis on the performance of the lower limbs. Our findings demonstrate an inflammatory response with hormonal changes after exposure to fire and an adaptive response of thermal balance, which could aid understanding of the physiology of the human body in extreme situations.
Les sapeurs-pompiers (SP) sont régulièrement exposés à la chaleur et aux produits de combustion, qui peuvent avoir un retentissement sur leur santé. Nous avons évalué l’effet d’une exposition aiguë de 22 SP (tous des hommes) à incendie simulé grâce à la répétition à 4 reprises d’une même batterie d’examens (avant- T0, et à la fin des 1ère -T1 2ème - T2 et 3ème - T3 semaines d’entraînement). Des paramètres sanguins relatifs à l’inflammation et l’immunité (CRP, IL6, IL10) ainsi qu’au système endocrinien (cortisol, testostérones totale, libre et biodisponible, SHBG, TSH et T4 libre) étaient prélevés à chaque évaluation. Une étude thermographique, évaluant la température corporelle et le flux thermique corporel était réalisée à T0, T1 et T3. On constatait une augmentation de la CRP et une baisse de IL10. On observait une augmentation de la cortisolémie ainsi qu’une baisse de thyroxine libre et testostérone biodisponible, cette dernière se normalisant à T3. L’adaptation corporelle à la chaleur se traduit par une augmentation du flux thermique, en particulier aux membres inférieurs. Nous observons donc des réponses inflammatoire comme endocrinienne et une adaptation de la thermorégulation en cas d’exposition à un incendie, constatations pouvant contribuer à la compréhension de la physiologie humaine en situations extrêmes.

The main goal of this study was to update the Finnish smoke-diving drill (FSDD) and to measure the physical strain of and recovery from the drill. Furthermore, the aim was to compare the physical strain of contract and professional firefighters and effect of floor materials. The associations between aerobic capacity and physical strain were also studied. The updates made included an added hose pull task and updating the equipment used. Heart rate (HR), oxygen consumption (V̇O2), and blood lactate concentration ([La-]) of 32 professional and 5 contract firefighters were measured before, during, and 10 and 30 min after the updated drill. The mean HR during the drill was 78% and V̇O2 59% of maximum. HR and [La-] had not recovered to baseline levels after 30-minute recovery period. Physical strain was higher among contract firefighters and [La-] accumulation on rough floor surfaces. Better aerobic capacity was associated with reduced physical strain.
The purpose of this study was to update the Finnish smoke-diving drill. This paper describes the process of updating the drill, and the experimental measurements regarding the metabolic demands of the updated drill. The updates made included adding a hose pull task and updating the equipment used during the drill.

Firefighters risk heat strain during occupational tasks when exposed to extremely hot environmental conditions and performing high-intensity work. Relevant training scenarios are therefore essential. This study investigated the effect of a single simulated smoke dive and the following recovery phase on physiological and perceptual responses. Nineteen professional male firefighters (43 ± 8 yr) performed a 2-min stair walk and a15-min simulated smoke dive in a two-floor heat chamber (110 °C to 272°C) (HEAT), followed by a 5-min stair walk outside the heat chamber. Heart rate (HR), gastrointestinal temperature (Tgi) and skin temperatures were registered continuously during the test. The Tgi increased significantly from the start (37.5 ± 0.3°C) to the end of HEAT (38.4 ± 0.4°C) and further increased after the heat exposure (39.6 ± 0.5°C).The HR also increased significantly from the start (92 ± 14 bpm) to the end of HEAT (185 ± 13 bpm) and increased after the heat exposure to a maximum of 190 ± 13 bpm. The simulated smoke dive induced high physiological strain on the firefighters, and the increase in Tgi and HR after the hot exposure must be considered during live fire events when repeated smoke dives are required.

Prostate cancer is the leading incident cancer among men in the United States. Firefighters are diagnosed with this disease at a rate 1.21 times higher than the average population. This increased risk may result from occupational exposures to many toxicants, including per- and polyfluoroalkyl substances (PFAS). This study assessed the association between firefighting as an occupation in general or PFAS serum levels, with DNA methylation. Only genomic regions previously linked to prostate cancer risk were selected for analysis: GSTP1, Alu repetitive elements, and the 8q24 chromosomal region. There were 444 male firefighters included in this study, with some analyses being conducted on fewer participants due to missingness. Statistical models were used to test associations between exposures and DNA methylation at CpG sites in the selected genomic regions. Exposure variables included proxies of cumulative firefighting exposures (incumbent versus academy status and years of firefighting experience) and biomarkers of PFAS exposures (serum concentrations of 9 PFAS). Proxies of cumulative exposures were associated with DNA methylation at 15 CpG sites and one region located within FAM83A (q-value <0.1). SbPFOA was associated with 19 CpG sites (q < 0.1), but due to low detection rates, this PFAS was modeled as detected versus not detected in serum. Overall, there is evidence that firefighting experience is associated with differential DNA methylation in prostate cancer risk loci, but this study did not find evidence that these differences are due to PFAS exposures specifically.

The aim of this study was to assess the exposures received by firefighters engaged in extinguishing the large-scale wildfires in the most contaminated areas of the Ukrainian part of the Chornobyl Exclusion Zone in 2016 and 2020. The assessments are based on measurements of radionuclide airborne concentrations in the breathing zones of workers and at the aerosol sampling stations of the automated radiation monitoring system operated by SSE Ecocenter. During the wildfires, the radionuclide airborne concentrations increased by orders of magnitude compared to the background levels, reaching maximum values in the firefighting area of 1.20 ± 0.01 Bq m-3 for 90Sr, 0.18 ± 0.01 Bq m-3 for 137Cs, (1.8 ± 0.3) ∙10-4 Bq m-3 for 238Pu, (4.5 ± 0.7) ∙10-4 Bq m-3 for 239-240Pu, and (8.0 ± 1.3) ∙10-3 Bq m-3 for 241Pu. The internal effective doses to firefighters due to inhaled radionuclides did not exceed 2 μSv h-1 and were 3-5 times lower compared to the external dose of gamma radiation. Thus, the time of firefighting in the ChEZ will be limited by the external dose.

In the present experiment, we evaluated the impact of rapid heat stress (RHS) on salivary cortisol and C-reactive protein production pre-RHS, post-RHS, and 24 and 48 h post-RHS exposure among firefighters. Previous research has demonstrated that RHS increases salivary cortisol during RHS and immediately post-RHS exposure. However, no research has evaluated the duration necessary to return to baseline cortisol levels following RHS. Additionally, no studies have analyzed the impact of RHS on inflammatory biomarkers, such as C-reactive protein. This study hypothesized that salivary cortisol and C-reactive protein levels would increase following RHS and then return to pre-RHS levels within 24 h post-exposure. Twenty-four participants performed a steady-state treadmill protocol in an environmental chamber (35 °C; 45% humidity) in full firefighter personal protective equipment until reaching either a core temperature (Tc) of 39 °C or a volitional maximum. The subjects had their saliva collected via the passive drool protocol pre-RHS, post-RHS, and 24 and 48 h post-RHS. Pre-RHS of 0.23 ± 0.03 μg/dL increased post-RHS to 0.51 ± 0.06 μg/dL (p < 0.001). This finding supports previous literature demonstrating the immediate impact of RHS. There were no changes in C-reactive protein. The novel finding of this study is that salivary cortisol levels return to baseline in the 24 h post-RHS exposure. This indicates that 24 h is recommended to recover from RHS and should be applied to prevent the chronic stress response.

Firefighters are required to perform physically strenuous tasks such as hose drags, victim rescues, forcible entries and stair climbs to complete their public safety mission. Occupational-specific tasks are often used to evaluate the ability of firefighters to adequately/safely perform their duties. Depending on the regions, occupational-specific tasks include six to eight individual tasks, which emphasize distinct aspects of their physical fitness, while also requiring different levels of cardiovascular (CVH) and musculoskeletal health (MSH). Therefore, the aim of this study was to evaluate the relationship between specific occupational task performance and measures of physical fitness, cardiovascular and musculoskeletal health.
Using a cross-sectional design, 282 full-time male and female firefighters were recruited. A researcher-generated questionnaire and physical measures were used to collect data on sociodemographic characteristics, CVH, MSH and weekly physical activity habits. Physical measures were used to collect data on physical fitness and occupational-specific task performance.
Absolute cardiorespiratory fitness (abV̇O2max), grip strength, leg strength, push-ups, sit-ups and lean body mass (all p < 0.001) had an inverse association with completion times on all occupational-specific tasks. Age was positively related to the performance of all tasks (all p < 0.05). Higher heart rate variability (HRV) was associated with better performance on all tasks (all p < 0.05). Bodyfat percentage (BF%) and diastolic blood pressure were positively associated with the step-up task (p < 0.05). Lower back musculoskeletal injury (LoBMSI), musculoskeletal discomfort (MSD), and lower limb MSD were associated with a decreased odds of passing the step-up. Upper body MSIs (UBMSI), LoBMSIs and Lower back MSD were associated with decreased odds of passing the rescue drag.
Firefighters that were taller, leaner, stronger and fitter with a more favourable CVH profile, higher HRV and less musculoskeletal discomfort performed best on all occupational-specific tasks.

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic to humans and are formed by incomplete combustion. PAHs are always present during firefighting operations, and fire department members can be exposed to them in the workplace.
In this study, we analyzed 1-hydroxypyrene (1-OHP) in 36 urine samples from nine firefighters, collected before and after fire training sessions, and 32 urine samples from eight employees at respiratory protection and hose workshops. To assess breakthrough PAH exposure through personal protective equipment and potential dermal uptake, some of the workshop employees wore cotton garments under their regular workwear. Cotton samples were then examined for the presence of 17 semi-volatile and low-volatility PAHs.
After firefighting exercises, we observed approximately a fivefold increase in mean 1-OHP concentrations in samples from firefighters, from 0.24 μg/L to 1.17 μg/L (maximum: 5.31 μg/L). In contrast, 1-OHP levels in workshop employees were found to be low, with the majority of urine samples yielding concentrations below the limit of quantification (LOQ: 0.05 μg/L, maximum: 0.11 μg/L). Similarly, low PAH levels were found on the workshop employees\' cotton undergarments, with maximum concentrations of 250 and 205 ng/g for pyrene and benzo[a]pyrene, respectively.
In conclusion, significant increases in 1-OHP in urine were observed in firefighters after training sessions, whereas work-related exposure remained low among workshop employees.