The relationship between thermal sensation and facial skin temperature with varying air temperatures

We explored the relationship between facial skin temperature and overall thermal sensation (OTS) in winter. Twenty healthy young participants experienced five air temperatures: 12℃, 15℃, 18℃, 21℃ and 24℃ in a climate chamber. The clothing insulation was about 1.1 clo. During 140-minute-long exposures to each condition, we collected their facial skin temperature, including forehead, nose, ears, cheeks, and chin, as well as OTS. We defined two periods during exposures: from 0 to 14 minutes and from 15 to 135 minutes. During the former period, skin temperature and OTS changed inconsistently with time and during the latter consistently. For all five temperatures, facial skin temperature was significantly different between the two exposure periods when feeling "cool/cold or slightly warm." During the 15 to 135 minutes period, most local facial skin temperatures strongly correlated with OTS. These results provide input to the theoretical basis when using facial skin temperature to monitor human OTS in the future.