2024 Yes Indoor and outdoor air concentrations of volatile organic compounds and NO2 in schools of urban, industrial and rural areas in Central-Southern Spain https://www.sciencedirect.com/science/article/abs/pii/S0048969717333326?via%3Dihub Villanueva, Florentina Europe Exposure Modeling Elementary (K-5) Volatile Organic Compounds (VOCs) Nitrogen Dioxide (NO2) Volatile organic compounds (VOCs) Carbonyl compounds Nitrogen dioxide (NO2) Indoor air quality School Spain Formaldehyde, hexanal, and n-dodecane were the most abundant VOCs measured in 18 schools across urban, rural, and industrial areas in Spain. Indoor sources dominated VOC levels, while NO₂ varied more by area. Policy should target indoor source control. 2018