Strategies to minimize SARS-CoV-2 transmission in classroom settings: combined impacts of ventilation and mask effective filtration efficiency

Strong evidence exists indicating that aerosol transmission of the novel coronavirus SARS-CoV-2 is a significant modality. We experimentally evaluated impact ventilation on dynamics and distribution along with effective filtration efficiency (EFE) four different mask types, without fitters, in classroom setting. These were used to estimate conditional infection probability using Wells–Riley model for three scenarios interventions. Aerosol measurements confirmed room was uniform within factor 2 distances >2 m from source. Mask EFE results demonstrate most masks fit poorly estimated leakage rates typically >50%. However, EFEs approaching material FE achievable fitters. Infection estimates indicate alone not able achieve probabilities <0.01 (1%). The use moderate high reduces probability, >5× some cases. Reductions provided by are synergistic multiplicative. reinforce properly donned reduced other infectious diseases motivate improvements through improved design or