Influence of air flow on skin temperature

The skin temperature is fundamental to heat exchange between the human body and the environment. The convective and evaporative heat exchanges depend on the temperature gradient and the extent of air flow over the skin surface. An attempt was made to study the topographical differences in skin temperature (Tsk) under varied levels of air flow and to examine the possible body temperature regulatory mechanism. Five volunteers were examined in a climatic chamber at 30 and 36 degrees C DB at 55-60% RH (ambient vapour pressure of 2.58 and 3.53 kPa and air flow of 0.6, 1.4, 1.9, 2.1 m/s). The deep body temperature (Tc) and local Tsk were recorded at 5-min intervals during 10 min pre-exposure, 30 min exposure to heat and 15 min recovery period after air flow was withdrawn. The time taken to attain at the lowest Tsk in different air speeds varied from 30 to 45 min. The highest drop in Tsk (2.4 degrees C) was recorded for forehead at 30 degrees C DB and significant skin cooling was achieved at an air flow of 0.6 m/s for most body regions. The overall drop in local Tsk was more greater at a higher ambient temperature (36 degrees C) and the changes were significantly different (p < 0.05) to those recorded at the preexposure level. There was a consistent drop in Tsk with time, while no definite pattern of drop was noted with the magnitude of air flow. The Tc increased significantly with the continued air flow and following withdrawal of air flow the Tc tended to drop, suggesting heat gain by the body with a consequent increase in Tc.