Abstract
To investigate methods of preventing heat disorders among firefighters, experiments that simulated firefighting activity were performed under normal ambient conditions in summer (35°C, 30°C, 25°C; 70% relative humidity, respectively). In these experiments, 16 male firefighters pedaled a bicycle ergometer wearing firefighting equipment, and the physiological responses and subjective sensations were measured. At 35°C, the interval until the inner ear temperature elevated to 39°C was 20.0 minutes and the sweat production rate was 2.5 kg/h. At 30°C, these values were 26.6 minutes and 2.0 kg/h, respectively. However, at 25°C, the inner ear temperature had elevated to only 38.5°C after 40 minutes (the end point of the experiment) and the sweat production rate was 1.7 kg/h. RPE of the Borg scale and thermal sensation points differed significantly (p<0.05) among the three environmental conditions. Both values correlated with inner ear temperatures (p<0.001, respectively). When firefighting activities are performed in an environment over 30°C, reexamination of clothes, measures such as body cooling, fluid intake, or activity breaks should be considered.
