Thermophysiology and Cognitive Performance of Live-Line Workers in High-Temperature and High-Humidity Environments

Live-line workers' physiological and psychological conditions are significantly affected when operating in high-temperature and high-humidity environments, influencing both work efficiency and safety. Fifteen participants, wearing high-voltage-shielding clothing, were tested in a simulated environmental chamber at temperatures of 23 °C, 32 °C, and 38 °C, and relative humidities of RH 30%, RH 50%, and RH 75%. The experiment involved walking at a speed of 5 km/h for 75 min., during which the participants' skin temperature, core temperature, thermal sensation, heart rate, blood oxygen level, sweat rate, and cognitive performance were measured. The results indicated a marked increase in both core and skin temperatures with rising temperature and humidity levels. At 38 °C/RH 75%, the core temperature reached 38.39 °C, and the average skin temperature was 36.8 °C. Significant differences in skin temperature were observed across different body regions (<i>p</i> < 0.05), with this disparity decreasing as the temperature increased. Heart rate, blood oxygen level, and sweat rate also exhibited significant differences across varying conditions (<i>p</i> < 0.05). Specifically, heart rate and blood oxygen level increased with higher temperature and humidity, while blood oxygen levels decreased as the environmental temperature and humidity increased. In addition, as temperature and humidity levels rose, the participants' error rate and average response time in cognitive tasks increased. The negative impact of temperature and humidity on performance efficiency and accuracy was more pronounced in complex cognitive tasks. The study further found that thermal sensation voting (TSV) remained within the range of -0.5 to +0.5, with the average skin temperature in the thermal comfort zone ranging between 33.4 °C and 34.1 °C. It is recommended that the environmental temperature in high-humidity conditions be maintained between 20.8 °C and 25.8 °C. Our findings provide a theoretical foundation for the development of personal protective equipment for live-line workers.