Hand skin temperature variations for work in moderately cold environments and the effectiveness of periodic rewarming

An investigation of skin surface temperature variations under actual work conditions for four locations on the hand studied the utility of hot water immersion sinks for restoring heat to the hands during exposure to moderately cold temperatures in a food processing plant. Hand skin temperature was recorded for 15 subjects in 2 jobs with an ambient temperature of 13.3 degrees C (56 degrees F) and 1 job with an ambient temperature of 23.9 degrees C (75 degrees F). Averaged over all jobs, the mean temperature for the dorsal and palmar third finger was 17.7 degrees C (63.9 degrees F), which was significantly (p < 0.01) cooler than the mean dorsal and palmar hand temperature of 28.9 degrees C (84.0 degrees F). There was no significant difference between dorsal and palmar temperatures for either the finger or the hand (p > 0.05). In the warm environment there were no significant differences in skin temperature for any of the four hand locations (p > 0.05). An exponential model of digital warming and cooling was empirically derived using 12 subjects for predicting finger skin temperature when periodically rewarming the hands using a hot water immersion sink. The dorsal and palmar finger had a mean time constant of 151 sec for warming during immersion, 640 sec for initial cooling after a 15- to 30-min rest break at room temperature, and 198 sec for cooling after rewarming in the hot sink. The sink did not appreciably raise minimum finger skin temperature after subjects rewarmed the hands for as long as 2 min and then worked for more than 10 min without a rewarming session.