The arduous conditions (i.e., harsh environmental conditions, high physical and mental demands) in which wildland firefighters (WFFs) have to perform their work during wildfire suppression can lead to states of both physical and mental fatigue. Although several studies have delved into the first type of fatigue, there is a paucity of research on the decrease in WFFs’ cognitive performance. A decreased cognitive performance has been observed throughout multi-day suppression tasks, which could lead to poor decision-making and have unintended consequences on deployments. To our knowledge, the acute effect of tasks performed by WFFs on cognitive fatigue has not been studied. Therefore, the aim of this study was to analyze the effect of performing a specific circuit, which simulated the tasks performed by WFFs in their deployments, on central nervous system fatigue. Ten WFFs (34.4 ± 5.6 yr, 182.9 ± 6.1 cm and 92.8 ± 14.9 kg) participated in the study, who performed a field test composed of 4 specific tasks commonly used in their deployments. Each task was executed for 5 min interspersed by 90 s of recovery. This interval bout was repeated twice with 10 min of recovery in between. During the test heart rate (HR) and core temperature (CT) response were monitored. Both variables were used to calculate the physiological strain index (PSI). In addition, before and at the end of the field test, subjects’ critical flicker fusion (CFF) threshold was measured. The results obtained showed that the WFFs performed a high-exercise demand (mean HR, 85.3 ± 2.5% of maximal HR; CT, 38.3 ± 0.4 ºC and PSI, 6.0 ± 0.7). Despite this, CFF threshold measurements showed an increase (6.0 ± 6.0%, p < 0.05) in the sensory sensitivity threshold, suggesting an exercise induced increase in cortical arousal. Significant (p < 0.05) relationships between sensory sensitivity and time spent at high percentage of maximal HR (>90%), TC and PSI were found (r = -0.71, -0.74 and -0.69, respectively). In conclusion, the specific field test led an enhancement of sensory sensitivity and cortical arousal. However, the correlations found seem to indicate the potential negative effect of high-intensity exercise and thermal strain on central nervous system fatigue.

Wildland firefighters (WFF) face a set of specific work-related factors that directly affect their physical and cognitive abilities and compromise their health and safety. The working conditions include hard physical work and environmental conditions that combine high temperatures and high radiant heat. Such environments make using personal protective equipment (PPE) mandatory to protect them from risks. This fact restricts heat removal and adds extra weight, increasing thermal strain and the risk of heat-related illnesses on WFF. Since the number of females WFF has increased, it is necessary to study the repercussions of heat stress on this group. To date, it is not yet well-known whether sex-related differences in thermoregulation will be relevant when the individuals are wearing PPE and performing high physical effort in a hot environment. Therefore, we aimed to investigate the physiological response when performing moderate to high-intensity effort in a hot-dry environment while wearing PPE according to sex. Twenty WFF 10 females [23.9 ± 3.2 yr, 163.8 ± 3.4 cm and 62.7 ± 9.1 kg] and 10 males [31.9 ± 6.6 yr, 178.8 ± 5.8 cm and 73.9 ± 7.7 kg]) performed a 125 min treadmill test in a controlled ambient (30 ºC and 30% relative humidity). The protocol consisted of two exercise stages where WFF performed different continuous and variable exercise bouts in order to mimic the effort performed during real deployments. Participants wore the full standard PPE during the test. Oxygen uptake (VO2), heart rate (HR), core temperature (CT) and chest temperature (SkT) were monitored throughout the test. HR and CT were used to calculate the physiological strain index (PSI). Differences in body mass pre-post trials corrected for fluid intake were used to calculate sweat production (SwP), sweating rate (SwR), and evaporative efficiency (EE). Differences (p < 0.05) between females and males were found in %VO2max (62.5 ± 7.4 vs 55.3 ± 5.), HR (155 ± 10 vs 134 ± 14 beats·min–1), % of maximal HR (81.3 ± 3.5 vs 42.3 ± 6.5), CT (38.0 ± 10 vs 37.7 ± 0.33 ºC), SkT (36.0 ± 0.6 vs 35.3 ± 0.6 ºC) and PSI (4.1 ± 0.5 vs 3.5 ± 0.6). Even though SwR was higher (p < 0.05) for male participants (1001.5 ± 268.3 ml) compared to females (647.5 ± 145.9 ml), females had higher EE (32.9 ± 4.6 vs 16.7 ± 6.2 %). In conclusion, performing high-intensity exercise in hot-dry conditions while wearing PPE leads to a higher thermal and cardiovascular load for female WFF, making them more susceptible to heat illness. These results could be linked to lower aerobic fitness, sweating rate, and hormonal aspects that increased the thermal burden.

RESUMENFundamento: Se ha descrito que la salud y el rendimiento labo ral del personal dedicado a la extinción de los incendios forestales se ven perjudicados principalmente por el monóxido de carbono (CO). El objetivo de este trabajo ha sido analizar la exposición al CO a la que se ve sometido el personal especialista en la extinción de los incendios.Métodos: Durante 58 incendios reales se monitorizó en 44 suje tos la exposición al CO a la que se vieron sometidos. También se ana lizó la concentración ponderada para una jornada de 8h (VA-ED). Todos los incendios fueron divididos en función del tipo de trabajo realizado (ataque directo, indirecto y combinado) y del combustible presente (pasto, matorral, bajo arbolado y mixto). Las variables ana lizadas fueron estudiadas mediante la prueba de Kruskal-Wallis, se usó el test de Mann-Whitney para establecer las diferencias entre medias.Resultados: La concentración media de CO en los incendios fue de 18,4±1,7 ppm, lo que supuso una VA-ED de 7,0±1,0 ppm. Las mayores exposiciones al CO se analizaron en los ataques combina dos (20,4±2,3 ppm) seguidas de las obtenidas en los ataques directos (17,5±2,7 ppm) e indirectos (10,6±5,4 ppm). Únicamente se obtu vieron diferencias significativas (p<0,05) al comparar las exposicio nes al CO generadas por la combustión del matorral (19,8±2,2) y bajo arbolado (17,2±3,9) y pasto (12,0±5,6).Conclusiones: Las exposiciones de CO analizadas se vieron influidas por el tipo de combustible y trabajo desempeñado. Los valores medios obtenidos se situaron dentro de los límites estableci dos como seguros por diferentes organismos nacionales (INSHT) e internacionales (NIOSH, OSHA). Background: Health and occupational performance in wildland firefighters are mainly impaired for the carbon monoxide inhalation. Therefore, the aim of this study was to analyze the personal exposu re to carbon monoxide in wildland firefighters during wildfires sup pression.Methods: Carbon monoxide exposure was monitorized in 44 subjects during 58 real wildfires. Moreover, we analyzed the time weighted average exposure for an 8h shift (VA-ED). The wildfires were classified according to the work done (direct attack, indirect attack and mixed attack) and the current fuel (grass, bush, understory and mixed).Results: The mean exposure to carbon monoxide was of 18,4±1,7 ppm, what supposed a VA-ED of 7,0±1,0 ppm. The highest exposures to carbon monoxide were found during the mixed attack (20,4±2,3 ppm) and direct attack (17,5±2,7 ppm). We only obtained significant differences (p<0.05) between bush (19,8±2,2) and understory (17,2±3,9) and grass (12,0±5,6).Conclusions: Exposures to carbon monoxide were influenced for the work done during the wildfires suppression and the type of fuel involved. Mean values obtained in this study were within safety limits described by different Spanish (INSHT) and international (NIOSH, OSHA) occupational safety and health agencies.