HEAT REACTIONS OF CAUCASIANS IN TEMPERATE, IN HOT, DRY, AND IN HOT, HUMID CLIMATES.

Abstract

Heat reactions of Australian Caucasians living in hot, humid climates and of French Caucasians living in hot, dry climates were compared to unacclimatized and highly acclimatized male Caucasians living in Johannesburg. The experiments were conducted in climatic chambers at temperatures of 90 F wet-bulb and 93 F dry-bulb, and a workload of 1 liter O2/min consumption. The Australians did not differ significantly from the French in the three reactions to heat, except for a slightly significantly higher sweat rate in the 1st hr. The French and Australians had lower mean rectal temperatures and heart rates and higher sweat rates than the unacclimatized South Africans. Although the trend is toward a significant difference for all hours, the differences are not always significant. Living and working in the hot, humid tropics and in the hot, dry desert evidently confers a certain measure of acclimatization to heat. Quantitatively this can be expressed as 50% of the difference between unacclimatized and acclimatized men. This is, however, considerably less than the condition achieved by systematic artificial acclimatization. Australian versus French Caucasians in heat reactions; effects of various climates on Caucasians; heat reactions in the desert; heat reactions in the tropics; physiological effects of hot, dry and hot, humid climates Submitted on August 19, 1963