2024 Yes From spontaneous to strategic natural window ventilation: Improving indoor air quality in Swiss schools https://www.sciencedirect.com/science/article/pii/S1438463921000614 Vassella, Claudia C. Europe Observational Experimental Elementary (K-5) Middle/Jr High (6-8) High School (9-12) Ventilation rates Carbon Dioxide (CO2) Natural window ventilation Carbon dioxide (CO2) Indoor air quality School Intervention Awareness-raising In Swiss classrooms with natural ventilation, CO₂ levels often exceeded hygiene limits. A low-burden intervention during breaks significantly reduced exposure. Strategic window ventilation offers a practical method to improve air quality in schools. 2021