Evaluation of Resting-State Cooling Effectiveness in Wearable Body-Cooling Devices Using Thermophysiological and Psychological Responses

Heat exposure in summer increases the risk of heat strain during work and rest, highlighting the need for effective cooling strategies. This study evaluated the cooling effectiveness of a fan-cooling jacket (FC) and a thermoelectric neck cooler (NC) under resting conditions in a hot and humid environment. Six healthy males completed three trials (no cooling, FC, and NC) in an environmental chamber (35 °C, 70% RH). Thermophysiological responses (mean skin temperature, armpit temperature, sweat volume) and psychological ratings (thermal comfort, wetness sensation) were simultaneously assessed. FC significantly reduced mean skin temperature, attenuated the rise in axillary temperature, and decreased sweat volume while also improving thermal comfort and wetness sensation. In contrast, NC provided only transient improvements in comfort and did not suppress the rise in axillary temperature; wetness sensation deteriorated over time, likely due to its localized and limited cooling area. These findings indicate that, under low-activity conditions, broad-area forced convection cooling is more effective for mitigating heat stress than localized neck cooling. The results highlight the practical utility of fan-cooling garments for rest periods and other low-intensity scenarios.