2021 No https://doi.org/10.1016/j.buildenv.2021.108042 Stabile, Luca Europe Experimental Modeling Students Teachers High School (9-12) Ventilation rates Carbon Dioxide (CO2) Viruses COVID rates Exhaled CO2 Virus transmission Air exchange rate Ventilation Schools SARS-CoV-2 Mass balance simulations quantified air exchange rates needed to keep SARS-CoV-2 transmission risk low in classrooms; results support CO₂-based feedback ventilation controls, offering actionable strategies for reducing airborne virus spread in schools during pandemics.