Manual performance in work specific tasks
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- Institutt for biologi 
Background: Exposure to cold is a major hazard for outdoor workers at gas and petroleum installations. Local cooling of the extremities impairs performance of work specific tasks. Purpose: The purpose of this study was to examine the effect of ambient temperature (Ta), different clothing concepts and exposure time on manual performance; tactile sensitivity, finger dexterity, hand dexterity and grip strength. We hypothesised that petroleum workers, wearing their standard protective clothing will, when they are exposed to realistic, low, ambient temperatures (<15°C), have are duction in manual performance over time. Method: 12 male (age 23 ± 1.7 years) subjects were exposed for five different (22, 5, -5, -15 and -25°C) ambient temperatures in which the clothing concepts were modified after standard recommendation for petroleum workers. For each condition the subjects completed five test cycles, each cycle consisting of four manual tests (Touch test, Purdue Pegboard, Complete Minnesota Dexterity Test, grip strength), during 108 minutes of exposure. Gloves were taken off only during the test cycles. In addition, subjective assessment of thermal sensation and thermal comfort, and oxygen consumption (VO2)were completed prior to each test cycle. Results: We found a decrease in finger and hand dexterity over time at -5, -15 and -25°C, and a correlation between finger skin temperature (Tfinger) and manual performance. There was a significant effect of temperature at 5 and -5°C in tactile sensitivity. There was no significant change ingrip strength between conditions. Thermal sensation of cold increased with increasing cold stress and corresponded with temperature measurements on the body. A significant decline in finger skin temperature, mean skin temperature (Tsk) and body heat content (Hb) occurred over time in all conditions. There was also a significant decrease in rectal temperature (Tre) at each condition, except at -25°C. Heat production (HP) did not differ between conditions. Conclusion: Standard protectiveclothing for outdoor workers at oil and gas installations is not adequate to maintain manual performance over time when activity level is low and ambient temperature below -5°C. Local cooling of the hands was the main cause of impaired manual performance, followed by reduction in body heat content and thermal discomfort.