Physical Work Limits for Toronto Firefighters in Warm Environments

Abstract

This study examined the relationship between time to reach critical end points (tolerance time [TT] and metabolic rate for three different environmental temperatures (25 degrees C, 30 degrees C, and 35 degrees C, 50% relative humidity), while wearing firefighting protective clothing (FPC) and self-contained breathing apparatus (SCBA). Thirty-seven Toronto firefighters (33 male and 4 female) were divided into four work groups defined as Heavy (H, n = 9), Moderate (M, n = 9), Light (L, n = 10), and Very Light (VL, n = 9). At 25 degrees C, 30 degrees C, and 35 degrees C, TT (min) decreased from 56 to 47 to 41 for H, 92 to 65 to 54 for M, 134 to 77 to 67 for L, and 196 to 121 to 87 for VL. Significant differences in TT were observed across all group comparisons, excluding M versus L at 30 degrees C and 35 degrees C, and H versus M at 35 degrees C. Comparing 25 degrees C to 30 degrees C, M, L, and VL had significant decreases in TT, whereas only VL had a significant decrease when 30 degrees C was compared to 35 degrees C. For 25 degrees C to 30 degrees C, the relative change in TT was significantly greater for L (37%) and VL (41%) compared with H (16%) and M (26%). For 30 degrees C to 35 degrees C, the relative change among the groups was similar and approximately 17%. During passive recovery at 35 degrees C, rectal temperature (T(re)) continued to increase 0.5 degrees C above T(re final), whereas heart rate declined significantly. These findings show the differential impact of environmental conditions at various metabolic rates on TT while wearing FPC and SCBA. Furthermore, these findings reveal passive recovery may not be sufficient to reduce T(re) below pre-recovery levels when working at higher metabolic rates in hot environments.

Physiological and psychological responses in Fire Instructors to heat exposures

“…The added burden of wearing protective clothing, which increases thermal strain by placing a greater metabolic cost and lowers heat loss opportunities for the individual, is likely to compound the problems of hypohydration. Further, reduced heat dissipation and sweat evaporation from the limited vapour permeability, continually increases body heat storage (Selkirk and McLellan 2004). This will be further affected by greater respiratory demands (Bygrave et al 2004) from the SCBA, causing greater rates of oxygen consumption and metabolic heat production, thus increasing the rate of body temperature and the risks for heat related illnesses.…”

Characterizing a Firefighter’s Immediate Thermal Environment in Live-Fire Training Scenarios

“…Furthermore, these physiology-focused studies typically employ temperatures that are relatively constant, which is different than the continuously varying temperatures typically encountered on the training ground ( Figure 9). As Selkirk and McLellan [23] have shown, physiological responses to activities in PPE are affected by the temperature of the environment, so these differences should be considered in future iterations of firefighter physiological studies where possible. Finally, the effect of heat flux on firefighter physiological responses has not been studied to the same level of detail as exposure to high ambient air temperature environments.…”

“…Some studies have utilized training drills with environmental temperatures less than 100°C in a live-fire burn structure to simulate fire ground activities [18][19][20][21][22]. More commonly, research groups have used a treadmill protocol in a temperature-controlled ( 25°C to 50°C) room [23][24][25][26][27][28]. While Selkirk and McLellan have shown that the physiological responses to activity in fire fighting PPE is affected by the ambient temperature of the testing environment, there are limited data available upon which to base the representative thermal conditions.…”

Physical Response of Human Body Wearing Self Contained Breathing Apparatus

“…하지만 개선된 소방방화복의 다층화된 구조는 무게를 증가 시켰으며 수증기의 배출이 어려워지고 열교환율이 감소하여 체온조절을 어렵게 만들었다. 이는 직무 수행시 소방공무원을 더욱 힘들게 하였으며, 다수의 연구자들은 소방방화복을 입고 작업시 에너지소모량을 증가시킨다고 보고하고 있다 (2,3) . (8) , NISOH (9) , ACGIH (10) (12) .…”