The thermal ergonomics of firefighting reviewed.
ABSTRACT The occupation of firefighting is one that has repeatedly attracted the research interests of ergonomics. Among the activities encountered are attention to live fires, performing search and rescue of victims, and dealing with emergencies. The scientific literature is reviewed to highlight the investigative models used to contribute to the knowledge base about the ergonomics of firefighting, in particular to establish the multi-variate demands of the job and the attributes and capabilities of operators to cope with these demands. The job requires individuals to be competent in aerobic and anaerobic power and capacity, muscle strength, and have an appropriate body composition. It is still difficult to set down thresholds for values in all the areas in concert. Physiological demands are reflected in metabolic, circulatory, and thermoregulatory responses and hydration status, whilst psychological strain can be partially reflected in heart rate and endocrine measures. Research models have comprised of studying live fires, but more commonly in simulations in training facilities or treadmills and other ergometers. Wearing protective clothing adds to the physiological burden, raising oxygen consumption and body temperature, and reducing the time to fatigue. More sophisticated models of cognitive function compatible with decision-making in a fire-fighting context need to be developed. Recovery methods following a fire-fighting event have focused on accelerating the restoration towards homeostasis. The effectiveness of different recovery strategies is considered, ranging from passive cooling and wearing of cooling jackets to immersions in cold water and combinations of methods. Rehydration is also relevant in securing the safety of firefighters prior to returning for the next event in their work shift.
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ABSTRACT: Cooling vests incorporated with phase change materials (PCMs) add extra insulation and restrict sweat evaporation. It is still unclear how much cooling benefit they can provide. The aim of this study was to investigate the torso cooling of the PCM vests in two hot environments: hot humid (HH, 34°C, 75% relative humidity (RH)) and hot dry (HD, 34°C, 37% RH). A pre-wetted torso fabric skin was used to simulate torso sweating on a thermal manikin. Three cooling vests incorporated with three melting temperatures (Tm) of PCMs were tested (Tm = 21°C, Tm = 24°C and Tm = 28°C). They were worn under a military ensemble (total thermal insulation 1.60 clo; evaporative resistance 0.0516 kPa·m2/W), respectively. In a HH environment all the three cooling vests provided effective torso cooling; in a HD environment the cooling benefit was negative. In both environmental conditions, the evaporative cooling was greatly restricted by the cooling vests. The study indicated that when wearing the protective clothing with the relatively low evaporative resistance and when sweat production was high, the cooling vests were effective in a HH environment, but not in a HD environment.Textile Research Journal 09/2012; · 1.14 Impact Factor
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ABSTRACT: The pack hike test (PHT, 4.83 km hike wearing a 20.4-kg load) was devised to determine the job readiness of USA wildland firefighters. This study measured PHT performance in a sample of Australian firefighters who currently perform the PHT (career land management firefighters, LMFF) and those who do not (suburban/regional volunteer firefighters, VFF). The study also investigated the relationships between firefighters' PHT performance and their performance across a range of fitness tests for both groups. Twenty LMFF and eighteen age-, body mass-, and height-matched VFF attempted the PHT, and a series of muscular endurance, power, strength and cardiorespiratory fitness tests. Bivariate correlations between the participants' PHT finishing time and their performance in a suite of different fitness tests were determined using Pearson's product moment correlation coefficient. The mean PHT finishing time for LMFF (42.2 ± 2.8 min) was 9 ± 14% faster (p = 0.001) than for VFF (46.1 ± 3.6 min). The pass rate (the percentage of participants who completed the PHT in under 45 min) for LMFF (90%) was greater than that of VFF (39%, p = 0.001). For LMFF, VO(2peak) in L min(-1)(r = -0.66, p = 0.001) and the duration they could sustain a grip 'force' of 25 kg (r = -0.69, p = 0.001) were strongly correlated with PHT finishing time. For VFF, VO(2peak) in mL kg(-1) min(-1)(r = -0.75, p = 0.002) and the duration they could hold a 1.2-m bar attached to 45.5 kg in a 'hose spray position' (r = -0.69, p = 0.004) were strongly correlated with PHT finishing time. This study shows that PHT fitness-screening could severely limit the number of VFF eligible for duty, compromising workforce numbers and highlights the need for specific and valid firefighter fitness standards. The results also demonstrate the strong relationships between PHT performance and firefighters' cardiorespiratory fitness and local muscular endurance. Those preparing for the PHT should focus their training on these fitness components in the weeks and months prior to undertaking the PHT.Applied ergonomics 09/2010; 42(3):411-8. · 1.11 Impact Factor
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ABSTRACT: This study examined the separate effects of caffeine and menthol on cognition and mood during simulated firefighting in the heat. Participants (N = 10) performed three trials in a counterbalanced order, either with 400 mg caffeine, menthol lozenges, or placebo. The simulated firefighting consisted of 2 bouts of 20-min treadmill exercise and one bout of 20-min stepping exercise in the heat with two brief 15-min rest periods between each exercise phase. Exercise induced significant dehydration (>3%) and elevated rectal temperature (>38.9 °C), for all three conditions. Neither caffeine nor menthol reduced perceived exertion compared to placebo (p > 0.05). Mood ratings (i.e., alertness, hedonic tone, tension) significantly deteriorated over time (p < 0.05), but there was no difference among the three conditions. Simple reaction time, short-term memory, and retrieval memory did not alter with treatments or repeated evaluations. Reaction accuracy from a math test remained unchanged throughout the experimental period; reaction time from the math test was significantly faster after exposure to the heat (p < 0.05). It is concluded that, exhaustive exercise in the heat severely impacted mood, but minimally impacted cognition. These treatments failed to show ergogenic benefits in a simulated firefighting paradigm in a hot environment.Applied ergonomics 07/2013; · 1.11 Impact Factor