In an effort to decrease the number of casualties caused by heatstroke, we used a survey to measure the effects of air-conditioned wear and the differences between morning and afternoon on the physiological responses and reported comfort levels and thermal sensations of construction workers in summer. Measurements of the thermal environment, such as air temperature, humidity, wind speed and MRT; physiological responses such as skin temperatures, tympanic temperatures, heart stroke, activity, and three-directional (X, Y and Z) acceleration; and the survey to assess psychological response were carried out at indoor and outdoor construction sites over four days each. There were sixty-six interior workers (IW), thirty-one with air conditioned wear (ACW) and thirty-five without ACW. There were thirty-two plumbers (PL), twenty with ACW and twelve without ACW. There were forty-two reinforcing bar placers (RBP), twenty with ACW and twenty-two without ACW. There were forty-four form workers (FW), twenty-four with ACW and twenty without ACW. These numbers are based on the number of working hours logged, not on the n umber of subjects participating in the survey.
Skin temperature of RBP and PL workers at the outer construction site with ACW were significantly lower than those without ACW (p<0.01). Tympanic temperature of RBP workers with ACW was significantly higher than those without ACW (p<0.001). Tympanic temperature of PL workers was significantly higher than those of RBP workers with ACW (p<0.05), and lower than that of RBP workers without ACW (p<0.01). Acceleration in the Y-axis, of workers at the outer construction site with ACW was significantly higher than those without ACW (p<0.001), probably due to movement for their walking. Acceleration in the X-axis of workers at indoor construction site was significantly higher than those without ACW (p<0.001), probably due to their increased activity in cutting boards and pipes.
The effects of ACW on comfort and thermal sensation were estimated as below.
The reported comfort level of four occupational workers at the indoor and outdoor construction sites with ACW were significantly higher than those without ACW (p<0.001). The reported thermal level of both IWs and PLs with ACW were significantly lower than that without ACW (p<0.001). The reported thermal levels of PWs with and without ACW were significantly higher than those of RBPs (p<0.001). Without ACW, the reported thermal level of the IWs was significantly lower than those of the PLs (p<0.05). The reported thermal level of workers in outdoor construction site with ACW was significantly lower than those without ACW (p<0.001).
Lastly, differences in the physiological and psychological responses between the morning and the afternoon were investigated at the indoor and outdoor construction sites. Tympanic temperature and activity of workers at the indoor construction site in the afternoon were significantly higher than those in the morning (p<0.01, p<0.05). Skin temperature of workers at outdoor construction site in the afternoon was significantly higher than those in the morning (p<0.01). It was suggested that the increase of casualties caused by heatstroke in the afternoon was due to these physiological parameters.
The effects of ACW on both the psychological and physiological responses such as skin and tympanic temperature of workers at outdoor construction site were significantly estimated. The differences between the skin and tympanic temperatures of workers at indoor construction site with and without ACW were so small, that the only significant differences between those with and without ACW were psychological responses.
