United States Department of Agriculture, Forest Service, National Technology and Development Program, Missoula, Montana.
United States Department of Agriculture, Forest Service, National Technology and Development Program, Missoula, Montana.
Wilderness Environ Med. 2021 Jun;32(2):149-159. doi: 10.1016/j.wem.2021.02.004. Epub 2021 May 28.
The purpose of this study was to evaluate heat stress occurring in wildfire management activities with variable environmental conditions.
Direct observation and real-time wireless physiological monitoring allowed for weather and physiological metrics, including heart rate, core temperature (T), skin temperature, and physiological strain index (PSI), of male (n=193) and female (n=28) wildland firefighters (WLFFs) to be recorded during wildfire management activities. Accelerometry data were used to categorize intensity level of activity.
Ambient temperature and relative humidity values were used to compute the heat index (HI; n=3891 h) and divided into quartiles (Q1: 13.3-25.1°C; Q2: 25.2-26.4°C; Q3: 26.5-28.9°C; Q4: 29.0-49.1°C). Activity levels remained relatively constant across all HI quartiles. The percentage of time spent performing moderate/vigorous activities was lowest during the hotter Q4 (Q1: 3%; Q2: 2%; Q3: 2%; Q4: 1%). Heart rate, T, PSI, and skin temperature associations with HI varied by resource type. Sixty-one percent of WLFFs (n=134) experienced a T ≥38.0°C, and 50% of WLFFs (n=111) experienced a PSI ≥6.0.
Heat stress was prevalent as WLFFs performed job tasks of varying intensities in all ambient conditions. Spontaneous bouts of arduous labor, duration of work shifts, and other occupation characteristics present the possibility for substantial durations of hyperthermia, although no heat-related injuries occurred in this study. Despite chronic exposure to rugged sloped terrain, load carriage, and environmental conditions, self-regulation and individual attention to managing work:rest appears to be the primary management strategy in mitigating excessive accumulation of body heat in this occupation.
本研究旨在评估在环境条件变化的野外火灾管理活动中发生的热应激。
直接观察和实时无线生理监测可记录男性（n=193）和女性（n=28）野外消防员（WLFF）在野外火灾管理活动期间的气象和生理指标，包括心率、核心温度（T）、皮肤温度和生理应激指数（PSI）。加速度计数据用于对活动强度进行分类。
环境温度和相对湿度值用于计算热指数（HI；n=3891 小时），并分为四分位数（Q1：13.3-25.1°C；Q2：25.2-26.4°C；Q3：26.5-28.9°C；Q4：29.0-49.1°C）。在所有 HI 四分位数中，活动水平相对保持不变。在更热的 Q4 中，进行中等/剧烈活动的时间比例最低（Q1：3%；Q2：2%；Q3：2%；Q4：1%）。心率、T、PSI 和皮肤温度与 HI 的关联因资源类型而异。61%的 WLFF（n=134）的 T≥38.0°C，50%的 WLFF（n=111）的 PSI≥6.0。
WLFF 在所有环境条件下从事不同强度的工作任务时，热应激普遍存在。尽管在这项研究中没有发生与热有关的伤害，但艰苦劳动的自发发作、工作轮班的持续时间和其他职业特征存在大量过热的可能性。尽管长期暴露于崎岖的斜坡地形、负重和环境条件下，自我调节和个人注意管理工作：休息似乎是减轻该职业体内热量过度积累的主要管理策略。
