Thermal reaction and manual performance during cold exposure while wearing cold-protective clothing

Subjects were exposed in a climatic chamber for 60min to air temperature at — 5, —15 and — 20°C wearing cold-protective clothing with cotton working gloves. Subjects were asked to perform a 15 s counting task using a manual counter as fast as possible with the right hand, at approximately 15-min intervals during cold exposure. Skin and rectal temperatures were measured. On cold exposure, skin temperatures and body temperatures dropped gradually; after 1 hour most sites were colder, especially hand and finger temperatures. Finger temperatures decreased gradually with time, and steeply at the lower air temperatures, being temporarily raised by the counting task performed and possibly by cold-induced vasodilatation. By contrast, the gradual decline in hand temperatures showed no such transient changes. The decline in task performance with time was greater the lower the air temperature. The performance at -20°C decreased significantly with each further 15min exposure in comparison with the values before cold exposure (p<0.025 or 0.001). Performance after 1 hour cold exposure was reduced to 85.0, 803 and 73.5% at -5, -15 and -20°C, respectively. There was a significant correlation between counting task performance and the skin temperatures of the hand, the finger and the upper arm, mean skin temperature and mean body temperature during cold exposure. The skin temperature of the hand and the mean skin temperature showed highest correlations. This manual task performance was not only influenced by the temperatures of the local parts, i.e. hand, finger and upper arm temperature, but also by the general thermal state of the whole body — shown as mean skin temperature and mean body temperature in cold working conditions wearing cold-protective clothing.