Fisiologiese reaksies as hittestres voorspellers

Abstract

High environmental temperatures are a common problem in South African industry and influence the health and performance of factory workers. The siting of industry along the coast (especially the Natal coast) and the highveld results in the additional problem of environmental temperatures in combination with both high and low humidity levels . In areas where the humidity levels are low (relative humidity of 30 - 40 %) the problem is not so great due to evaporative cooling; the most effective cooling mechanism available to man during exposure to heat. At high humidity conditions (relative humidity of 70 - 90 %) and high temperature the effectiveness of evaporative cooling as a cooling medium is considerably lowered as can no longer easily take place . evaporation Bearing in mind the occurrence of reduced evaporative cooling at revised humidity levels then one is faced with the question of the value of WBGT as an index of the effectiveness of sweat evaporation in hot/humid conditions. The purpose o f this study was therefore the evaluation of the WBGT index in hot/humid conditions. Physiological parameters such as rectal temperature, heart rate, sweat rate and mean skin temperature were used as indicators of heat stress. Each of these parameters was measured at low and high relative humidities at environmental temperatures of 24 , 28 , 30 and 32 - c. As the physiological parameters were the major criteria for evaluation it was also possible to emulate their role as heat stress predictors.