2024 Yes Key Factors Determining Indoor Air PM10 Concentrations in Naturally Ventilated Primary Schools in Belgrade, Serbia https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5639812/ Matic, Branislava Europe Observational Modeling Students Elementary (K-5) Temperature Humidity Carbon Dioxide (CO2) Carbon Monoxide (CO) Particulate Matter (PM) Indoor air quality Classrooms Particulate matter (PM) respirable particulate matter (PM10) Primary schools Exposure Serbia IAQ and PM10 were measured over 5 days in 44 classrooms with 735 children. High PM10 was linked to overcrowding, poor ventilation, and thermal discomfort. Results support improved ventilation and space standards to reduce exposure in primary schools. 2017