Associations between thermal perception and physiological indicators under moderate thermal stress

Abstract

This study reports the findings from subjective responses of tropically-acclimatized people and their relationships with cutaneous indicators at three air temperatures, i.e. 20.0, 23.0, and 26.0°C. A blind intervention study was conducted in a simulated office environment. Ninety-six subjects were recruited and divided into 6 groups of 16 subjects. Each group was asked to perform simulated office tasks in the room for a continuous four-hour session. The subjects also completed surveys on general thermal comfort and sensations at various body locations. Measurement of skin temperature was carried out at five locations of the body, i.e. forehead, upper arm, hand, back, and foot, while sweat rate was measured at the upper arm. Correlation analysis was performed on both the subjective and physiological data. Subjects were unable to maintain thermal neutrality during the four-hour exposure at 20.0 and 23.0°C (P<0.0001). They felt most comfortable at 23.0°C (P<0.0001) despite reporting a slightly cool thermal sensation. Reduction of skin temperature was more profound at the extremities of the body, i.e. the hand and foot, under exposure of 20.0°C. Mean skin temperature appeared to be a strong predictor of the body thermal sensation.