The combined impacts of indoor temperature and total volatile organic compounds on cognitive performance of university students: A controlled exposure study

Volatile Organic Compound (VOC) emissions from building materials increase at high indoor temperatures, especially in newly built and refurbished buildings. With climate change driving indoor overheating, future students may face elevated indoor temperature and Total Volatile Organic Compounds (TVOC) levels simultaneously. This study investigated the combined impacts of temperature and VOCs on human cognitive performance. Seventy-one university students participated in an experiment conducted in a controlled climate chamber using a single-blind, 2 × 2 within-between participant design. The study employed two temperature levels (23 °C vs. 28 °C, within participants) and two TVOC concentrations (100 μg/m³ vs. 1000 μg/m³, between participants). Cognitive performance was assessed by a computer-based test battery. Participants' perceptions of thermal sensation, air quality and physical symptoms were collected via a paper-based questionnaire. Results indicate that temperature significantly impacts task accuracy, while TVOC levels do not. There was no clear evidence that either temperature or TVOC levels affected reaction speed. There was no interaction effect between temperature and TVOC level. Within-group tests showed a significant accuracy impact in six of ten tasks at 28 °C under 1000 μg/m³ TVOC, with an average task error increase of 5.2 %. Higher temperatures led to worse perceived air quality. During exposure, symptoms such as eye irritation and fatigue developed. These findings suggest that indoor overheating affects cognitive function and overall well-being. Future standards for VOCs may need to be adjusted based on temperature. It is important to propose a lower limit for TVOC at higher temperatures, as this is crucial for managing both overheating and TVOC levels during the summer.