Combined effects of ventilation rates and indoor temperatures on cognitive performance of female higher education students in a hot climate

Impairment in mental functions attributed to the effects of indoor air quality and thermal conditions has received considerable attention in the past decade, particularly for educational buildings where students' cognitive performance is essential to foster learning. This study explores the combined effects of indoor temperatures and CO2 levels as markers for ventilation rates on cognitive performance among female students (16-23 years old) in Saudi Arabia. The longitudinal experiments involved nine conditions combining three CO2 concentration levels (achieved via changes in ventilation) and three temperature levels involving 499 participants, all exposed to the nine conditions. The study implemented a computer-based cognitive performance battery with "9Button" keyboards. Univariable and multivariable multilevel regression models explored the association of indoor temperature and CO2 levels (as markers for ventilation rates) with cognitive performance after adjusting for potential confounders. Potential benefits were found on speed and accuracy of tasks of cognitive performance when indoor temperature was set between 20 and 23oC and at CO2 levels of 600 ppm compared to higher temperatures and poorer ventilation rates and that both ventilation and thermal environmental control are important and need to be improved for achieving optimum learning conditions. Nevertheless, the results are relevant for short-term exposures lasting no more than 2 h.