Thermal Stress and the Contribution of Radiant Heat

Abstract Sixteen young, healthy volunteers were exposed to eight thermally severe environments, each subject being exposed to four different climates. Four climates had a radiant heat component; globe temperature some 10°C above dry bulb. In the other four climates, the globe temperature was close to the dry bulb. Measurements of endurance time in the different climates were made, as were changes in deep body temperature and heart rate. The relationship between the wet bulb globe thermometer index (WBGT) and stay times in the non-radiant climates agreed well with that of previous workers. Further, the WBGT index appeared adequate, in the situation under study, in terms of its ability to quantify climatic severity, thermal and cardiovascular stress and hence endurance in climates with a high radiant heat component.