2025 Yes https://doi.org/10.1016/j.anpedi.2025.503792 Pérez-Moneo, Begoña Europe Observational Exposure Study Students Staff Elementary (K-5) Temperature Humidity Carbon Dioxide (CO2) Particulate Matter (PM) Volatile Organic Compounds (VOCs) Child Schools Indoor air quality Particulate matter (PM) A longitudinal study measured PM2.5, CO2, VOCs, temperature, and humidity in four Madrid schools. PM2.5 and VOCs exceeded thresholds in a large share of samples, underscoring the need for improved indoor air quality management in schools.