08/26/2021
Emphasis should be on increased ventilation. This study shows cloth & surgical masks that most students/people wear are only 10% effective at stopping covid style aerosols.
From this study: https://aip.scitation.org/doi/10.1063/5.0057100
Even the most professional of masks (R95) only reaches 60% effectiveness of stopping COVID aerosols:
"Nevertheless, high-efficiency masks, such as the KN95, still offer substantially higher apparent filtration efficiencies (60% and 46% for R95 and KN95 masks, respectively) than the more commonly used cloth (10%) and surgical masks (12%), and therefore are still the recommended choice in mitigating airborne disease transmission indoors. "
It is also clear that ventilation is a simple mitigation strategy that is more effective than the best masks:
"The results also suggest that, while higher ventilation capacities are required to fully mitigate aerosol build-up, even relatively low air-change rates lead to lower aerosol build-up compared to the best performing mask in an unventilated space.”
You can see how aerosols flow around different masks here:
https://www.youtube.com/watch?v=PtEYI4erRmM
More on the Effectiveness of Masks
From this source: https://swprs.org/face-masks-evidence/
You can see the lack of evidence of mask effectiveness.
