The effect of safety hat on thermal responses and working efficiency under a high temperature environment.

The purpose of this study is to examine the effect of a safety hat on thermal responses and work efficiency under a high temperature environment. Five healthy male subjects participated in the repeated 'Rest' and 'Exercise' periods in order to compare a safety hat without holes (annoted as 'without hole') and a safety hat with holes (annoted as 'with hole') in a climatic chamber of 30 degrees C, 50%RH. The main findings are as follows: (a) the core temperature (tympanic temperature) and heart rate showed significantly lower levels in the subjects who are under the 'with hole' condition than those who are under the 'without hole' condition; (b) the forehead skin temperature was significantly higher in the subjects who are under the 'without hole' condition than those who ar uder the 'with hole' condition; (c) blood pressure was significantly lower in the 'with hole' condition; and (d) sweat rate which was measured by weight loss before and after the experiment was higher in the 'without hole' condition; and (e) work ability which was measured by a grip strength dynamometer was higher in the 'with hole' condition. Making a hole in the safety hat, designed for proper ventilation and hygiene, is practical in letting out heat and decreasing the physiological burden under a hot working environment. The safety hat with holes is useful in maintaining the homeostasis of the body temperature by releasing body heat efficiently and it is meaningful to keep the working efficiency.