Ethnic differences in thermal responses and comfort sensation between Japanese and Caucasian young males under a temperate environment

This study has been made to examine ethnic differences in thermal responses and human thermal comfort sensation between Japanese and Caucasians under a temperate environment. Young healthy Japanese and Caucasian males voluntary participated in the present study. In the study, they firstly kept a rest condition and walked on a treadmill in the exercise condition. Japanese showed significantly higher mean skin temperature than Caucasian during a whole period of the experiment. Although the water vapour pressure over the skin surface during the rest was statistically slightly higher in Caucasian than in Japanese, calculated evaporation rate from the body surface in Japanese was significantly larger than that in Caucasians. This was because the temperature difference between the skin surface and the environment was larger in Japanese than in Caucasians. Calculated evaporation rate from the body surface during the exercise was found to be significantly larger in Japanese than in Caucasian because both of temperature and water vapour pressure of the skin surface showed remarkably higher values in Japanese than in Caucasians. Thermal comfort limit was discussed using skin wettedness based on linearity between the voted thermal comfort sensation and skin wettedness. The thermal comfort limits of the whole body were 0.39 ±0.05 in Japanese, and O.34 .± 03 in Caucasians. The thermal comfort limit in Japanese was found to be statistically equal to that in Caucasian.