Die ontwikkeling en evaluering van 'n hittetoleransietoets vir toepassing in die Suid-Afrikaanse mynindustrie

Thesis (M.Sc.)--PU vir CHO, 1983There is sufficient evidence to indicate that man's inherent ability to work in heat is subject to considerable variation. In the interests of productivity, health and safety, it follows that the identification of individuals with a degree of natural heat tolerance sufficiently high to obviate formal heat acclima­tization, would be of paramount importance, especially in the South African gold mining industry. In order to identify the hyper-heat-tolerant individuals (i.e. those who do not benefit from formal heat acclimatization), se­lected unacclimatized subjects were subjected to a four-hour block-­stepping routine at an external work rate of 54 Win a climatic room controlled at a wet-bulb temperature of 31,7 °C and a relative humidity of 90 per cent. Rectal temperature after the fourth hour was used as a criterion of heat tolerance. The validity of this procedure as a heat tolerance test and the subsequent classifica­tion of subjects as hyper-heat-tolerant were evaluated in terms of norms applicable to workers acclimatized by conventional means. The results of this study indicate that a heat tolerance test con­ducted at a work rate of 54 Win the above environment is a valid way of assessing the degree of natural heat required and that in­dividuals with fourth-hour rectal temperatures equal to or less than 38,5 °C can be classified as hyper-heat-tolerant. These men are unlikely to benefit significantly from formal heat acclimatiza­tion. Moreover they also display a lower risk of developing hyperthermia than acclimatized men. The physiological superiority of the former group appears to be related primarily to a remarkably responsible sweat mechanism. The application of a heat tolerance test in the mining industry holds considerable economical advantages. It also constitute a selection method to provide manpower for arduous tasks in hotter areas. More important, however, is the positive influence if will have on worker morale. Its introduction is recommended on an industry-wide basis.Master