Assessment of Physiological Severity of Hot Climates

¹ From the Medical Research Council Unit for Research on Climate and Working Efficiency, Department of Human Anatomy, Oxford, England

Ten healthy, young, acclimatized men were exposed to eight different climates to assess the accuracy of the Effective Temperature scale and the P4SR scale. The subjects remained seated throughout the exposures to heat, to approximate the metabolic conditions of the experiments from which the Effective Temperature scale was originally devised. Climates with the same Effective Temperature did not result in the same physiological stress as judged by tolerance times, rectal temperatures, pulse rates, skin temperatures and forearm blood flows; the scale proved inadequate as a method of predicting the relative severity of these environments. The P4SR scale, however, accurately predicted the order of severity of the eight climates investigated and can be used confidently within the range of environment and conditions investigated.