ePO 125 – Levels and temporal variability of total volatile organic compounds in primary school classrooms

Schools are critical social infrastructures and represent the main indoor environments for children outside their homes. Due to high occupancy–up to 4 times that of other public workplaces–school classrooms frequently face significant and adequate indoor air quality in classrooms is critical for the health and overall well-being of both students and teachers.  Volatile organic compounds (TVOCs) are among the relevant air pollutants, some of which may cause short- and long-term adverse health effects. In densely populated environments, humans and their activities can significantly contribute to local VOC flux, potentially affecting local air quality. Given the possible health risks, the World Health Organization (WHO) identified 30 chemicals relevant to indoor air that require attention, out of which 17 were VOCs. Thus, this study aimed to investigate levels of total VOCs (TVOCs) in nine primary schools (S1–S9).

Real-time TVOCs were continuously monitored by VelociCalc^® Multi-Function Ventilation – model 9565, TSI Inc., Shoreview, USA. In each school, the sampling was done in four classrooms (n=36) over five weekdays, both during heating and non-heating seasons (February–June 2024); logging time of 1 min was used to obtain a large temporal distribution of the data. The results showed that when occupied, the median TVOC ranged from 7.8–1780 µg m^–3 (total mean of 562 µg m^–3) across all classrooms, being up 36 times higher than when not occupied. The health-protective threshold of 600 µg m^–3 was exceeded in 34% of the assessed classrooms, highlighting the need for targeted IAQ management strategies in schools to mitigate health risks and ensure safe, comfortable learning environments for students and teachers.

Acknowledgment: This work was financed through EDC(Mind)² (PTDC/CTA-AMB/3040/2021, FCT PT) and the doctoral fellowships 2022.11261.BD and 2024.02722.BD.ANA.