Energy cost and thermal contribution of components of protective firefighter gear
Firefighter turn-out gear negatively impacts firefighters' ability to dissipate heat and increases energy expenditure consequently decreasing work tolerance and efficiency. The purpose of this study was to determine the contribution of individual components of firefighter turn-out gear to the energy expenditure and heat retention during work in a hot environment. Male participants (n=8) (Mean ± SD: 24.8 ± 2.6 yr, 73.1 ± 9.8 kg, 181 ± 4 cm, 57.3 ± 8.8 mlkg⁻¹min⁻¹ VO₂ max) worked for 40 min (12 min walk followed by 3 min of 10 arm curls) on a treadmill at a speed and grade eliciting 50% of VO₂ max in a heat chamber (WBGT: 33°C, RH: 40-45%) while wearing firefighter turn-out gear and a breathing apparatus (SCBA). Energy expenditure was measured during work to assess the energy costs of five firefighter turn-out gear configurations (full gear, trousers, coat, SCBA alone, and peripherals: helmet, hood and gloves (HHG)). Mean walking and arm-curl VO₂'s were not significantly different (p > 0.05) among any of the gear combinations. Mean delta (T₄₀-T₀) heart rate (ΔHR) was significantly higher (p = 0.01) for full gear (85 ± 25 beatsmin⁻¹) compared to trousers (53 ± 16 beatsmin⁻¹), SCBA (57 ± 13 beatsmin⁻¹), and HHG (58 ± 17 beatsmin⁻¹). In addition, mean delta body core temperature (ΔTre) was significantly higher (p < 0.05) for full gear (1.4 ± 0.4°C) compared to coat (0.8 ± 0.3°C), SCBA (0.8 ± 0.4°C), and HHG (0.8 ± 0.2°C). Ratings of Perceived Exertion (RPE) were significantly higher (p < 0.05) for full gear (9 ± 3) compared to trousers (6 ± 2), coat (6 ± 3), and HHG (6 ± 2). Each component of the firefighter turn-out gear similarly increased VO2 and hampered heat dissipation in a hot and humid environment. Although, the SCBA accounted for over half of the total weight of the firefighter gear, it made a similar contribution to the thermoregulatory demands as other pieces of equipment. Availability of lighter and safer protective clothing and SCBA could reduce physiological stress and potentially improve rescue time, but there appear no clear advantages to improving any particular piece of gear.