Heat stress of women doing manipulative work

Six women were exposed to nine environmental conditions, ranging from 26.0 to 35.8 degrees C effective temperature (ET), in a climatic chamber. They were involved in manipulative work in a seated position for a duration of 3 hr. The O2 uptake, heart rate, deep body (Tc) and skin temperature (Tsk), sweat loss, and perception of thermal comfort were noted. The O2 uptake increased with the time of exposure at different heat levels. The work energy demand, which was 19% of VO2max at 26 degree C ET, increased to 35% of VO2max at 35.8 degrees C ET. However, the work output declined with the increase in ET. Thus, the elevated metabolic demands were the results of the thermal stimuli. The Tsk was greatly influenced by the environmental heat; the Tc changes were gradual. The highest mean Tsk attained was 37.3 degrees C at 33.8 degrees C ET when the gradient of Tc-Tsk was only 0.5 degrees C. The rate of change in mean Tsk for 31.6 to 33.8 degrees C ET was much faster compared to the range between 26.0 and 31.6 degrees C ET. From 32.1 degrees C ET onward the Tc and heart rates rose rapidly, while the sweating rate tended to fall, indicating some hindrance for evaporative cooling. Also, thermal sensations were noted as extremely hot for the conditions 32.1 to 35.8 degrees C ET with the increase in exposure duration.