Thermal perception and skin temperature in different transient thermal environments in summer

The effects of air temperature up-step and down-step changes within one test which includes one high-level heat exposure stage and two low temperature stages on subjects' thermal perceptions and skin temperatures were studied. The air temperature of the high-level heat exposure stage was 37 °C while the low-level temperatures were 22/26/32 °C, thus developing large (C15: 22 °C-37 °C-22 °C), medium (C11: 26 °C-37 °C-26 °C) and small (C5: 32 °C-37 °C-32 °C) step-change conditions. Twenty four healthy subjects were recruited with skin temperatures of seven local body parts sampled. In addition, self-reported symptoms and thermal perceptions including thermal sensation, comfort and acceptability were investigated. Results show asymmetry in overall and local thermal sensation with overall and local ΔTSV after down-steps in C5 and C15 being significantly larger than their counterparts after up-steps. The most sensitive parts are back, arm and leg. Besides, overall thermal sensation change is more intensive than that of any of other local thermal sensations. In the large step-change condition C15, instep temperature contributed most to the fact that more than 45 min was needed for mean skin temperature to achieve steady after down-step.