Indoor air quality (IAQ) and thermal comfort are key components of indoor environmental quality (IEQ), particularly in educational buildings, as children spend a significant proportion of their day there. This study presents preliminary findings on IAQ and thermal comfort conditions in school classrooms in the Southern Douro Region of inland northern Portugal. Environmental parameters such as temperature, relative humidity, carbon dioxide (CO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and particulate matter (PM10 and PM2.5) were monitored in 15 spaces across seven school buildings.
The results show that CO2 concentrations in all of the classrooms regularly exceeded the protection threshold defined in Portuguese legislation (SCE), during periods of occupancy. CO2 levels were found to increase steadily during class time, indicating insufficient ventilation, whether natural or mechanical, during occupancy. There was a strong correlation between indoor temperature and outdoor ambient conditions, revealing limited climate control effectiveness.
The ambient air quality around the schools was generally classified as ‘good’, suggesting that in regions with low outdoor pollution levels, fresh air flows using outdoor air could be a viable solution for improving IAQ without introducing harmful pollutants. The findings also highlight issues such as the poor maintenance of HVAC systems and inadequate ventilation strategies.
These preliminary insights underscore the importance of targeted interventions, including proper ventilation design and regular maintenance, to ensure healthy indoor environments that support students’ well-being and performance.