Impact of air conditioning environments on human comfort through exhaled breath and physiological assessments in middle-aged women

Abstract

Optimizing indoor thermal environments is crucial for enhancing human comfort, particularly in the context of global warming. By innovatively integrating metabolomics, physiological monitoring, cognitive performance analysis, and subjective comfort evaluations, this study investigated the impacts of three air conditioning (AC) environments on human comfort in 20 middle-aged women volunteers. The three conditions were as follows: (A) refreshing mode, (B) cooling and floor heating modes, and (C) cooling mode at 24 °C with RH 50%. Evaluations included subjective comfort questionnaires, cognitive tasks, blood pressure measurements, exhaled breath analysis, and physiological monitoring via wearable devices. The results showed that Condition A provided the most stable blood pressure readings and excelled in tasks requiring creativity and memory, highlighting its balanced benefits for overall well-being. Condition B achieved the highest overall comfort scores and enhanced autonomic stability. Condition C facilitated superior performance in computational and logical reasoning tasks. The exhaled breath of the volunteers before and after exposure to each AC environment showed large differences based on semi-quantitative and quantitative analysis of exhaled breath components. These findings underscored the importance of tailoring thermal environments to optimize comfort, physiological health, and cognitive function, although the different condition modes were imperceptible. The integration of physiological data with subjective assessments provided a deeper understanding of how indoor conditions affect human well-being.