Local skin thermal responses to heat radiation.

Infrared heat radiation was directed onto the backs of healthy female subjects wearing a white or a black dress. Local skin thermal reactions of the back and the thigh were observed with reference to clothing color in a climate chamber where the ambient temperature was set at 20, 25 or 30 degrees C. Heat flow, skin temperature and air temperature under the clothing were measured. In the absence of radiation, skin temperature was higher than air temperature under clothing on the back and the thigh. Heat radiation caused both skin temperature and air temperature under clothing to rise, but the rise was considerably greater with black clothing than with white. As the effect of radiation was indirect, heat flow direction at the thigh was the same as in the absence of radiation. The thermal resistance index was calculated from skin temperature, air temperature under clothing and heat flow. Upon radiation exposure, the index of a black-clothed back tended to decrease with rising globe temperature. On the contrary, the index of a white-clothed back increased from a low negative value. This index is useful in assessing the skin-cloth system.