Abstract
In order to examine whether identical WBGT levels achieved by different combinations of environmental thermal parameters result in equivalent physiological responses, three fit young men were exposed for 2 hours at WBGT levels of 85°F and 89°F, each under four different combinations of natural wet bulb, globe temperature, and air speed. Air temperature and metabolic work were kept constant, at 96°F and 289 kcal/hr, respectively. Heart rate, rectal temperature, forehead skin temperature, and sweat loss of the subjects were determined during the steady-state phase of the exposures. It was found that condition in which the ambient humidity was relatively higher resulted in higher heart rate, body core temperature, forehead temperature, and sweat loss. Under dry conditions, the strain of exposure at WBGT 85 and 89 could not be differentiated. Under these conditions computed HSI values and observed Botsford wet globe readings were better indicators of relative strain resulting from the exposures than WBGT.