Heat reactions of male and female Caucasians

¹ Human Sciences Laboratory, Transvaal and Orange Free State Chamber of Mines, Johannesburg, South Africa

Thirty male and twenty-six female Caucasians were tested at work levels of 1.0 liters O₂ consumption in 90 F wet-bulb temperature, 93 F dry-bulb temperature, and 80 ft/min air velocity for comparative heat reactions in the unacclimatized state. The females had more severe physiological and psychological reactions. Rectal temperatures of 104 F and heart rates of 180 beat/min were reached more rapidly than in the male. The females sweated less and their oxygen consumptions were lower than those of the males. Ten males and four females were then acclimatized to the same extent at the same work rate in 93 F wet-bulb temperature. At the end of the period their reactions were closely similar, although the females responded slower to the acclimatization procedure. Both groups ended with heart rates of 140 beat/min and rectal temperatures of 102 F. The females, however, continued to sweat less. In a retest at 90 F wet-bulb temperature, both groups had heart rates of 130–140 beat/min and rectal temperatures of 101 F. Females still sweated less. The results demonstrate the fact that females react more severely on exposure to severe heat and work conditions. Once acclimatized, however, the temperature and circulatory reactions of both sexes are closely similar, but the females sweat less than males.

Submitted on September 14, 1964