An investigation of thermophysiological responses of human while using four personal cooling strategies during heatwaves

This study aimed to examine how human body thermophysiologically responds to four commonly used cooling strategies (i.e., electric fan cooling [AirFC], evaporative cooling clothing [EvapCC], hybrid cooling, i.e., evaporative cooling clothing combined with electric fan cooling [EvapCC&AirFC] and liquid cooling clothing [LiqCC]) during heatwaves. An adaptive 'Newton' manikin was used to predict human physiological responses while using these four cooling systems. Four heatwave conditions were selected, i.e., 36 °C, 33% RH (hot-dry, denoted as HD1), 36 °C, 67% RH (hot-humid, denoted as HH1), 40 °C, 27% RH (extremely hot-dry, denoted as HD2) and 40 °C, 54% RH (extremely hot-humid, denoted as HH2). A metabolic rate of 2.5 METs was used to mimic moderate work while sitting at either home or outdoors. AirFC was only found to bring cooling benefits in HD1 and HH1. EvapCC was effective in both HD1 and HD2. LiqCC showed similar cooling benefits compared to EvapCC in HD1 and HD2, and also displayed cooling benefits in HH1. EvapCC&AirFC was discovered to be most effective cooling strategy in the four studied conditions. Concerning their practical applications, EvapCC&AirFC was recommended to inactive populations while staying indoors during different heatwave conditions, and EvapCC and LiqCC were more suitable for active populations while working/exercising in hot-dry conditions and hot-humid conditions, respectively.