Empirical Study of the Manual Performance Disability Caused by Exposure to Extreme Cold Air among Auto Mechanic Workers

A decrease in body temperature can impair manual performance leading to a lowered capacity to carry out a certain activity. This study was aimed to analyze the extent effects of extreme cold air exposure on workers’ manual performance. The study population was consisted of 50 outdoor auto mechanics that were participated in two experiments carried out in winter and spring. Following a standard method, air environmental factors in each workstation and the physiological responses of the participants were measured. Touch sensory test was conducted to determine the sensory function of the hand. The grip strength and manual dexterity tests were also performed to assess manual work disability. The hand grip and pinch grip strength of the auto mechanics were reduced by 10.3% and 10.1% in cold air, respectively, as compared with the neutral air. Manual dexterity of the auto mechanics was also decreased from 6.3% to 8.8 % in cold air, as compared with neutral air. The prevalence of finger sensation disorders in the auto mechanics was 62% in cold air, while it was only 4% in neutral air. There was also a significant correlation between finger skin temperature and manual dexterity (r=-0.80, p<0.01), hand grip strength (r=0.74, p<0.01), and pinch grip strength (r=0.79, p<0.01). There was also a significant correlation between finger sensory function and manual dexterity (r=0.65, p<0.01). During extreme cold air exposure, the physiological and sensory changes have significantly reduced the manual performance of the auto mechanics. This study were able empirically provide a database for further researches on other aspects of the performance of workers exposed to cold air.