evidence: Some N95 masks, and even some cloth masks, have valves that make them easier to breathe through. But these masks don't filter the air the wearer breathes out. For this reason, they've been banned in some places. [...] - Chu DK, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: A systematic review and meta-analysis. The Lancet. 2020; doi:10.1016/S0140-6736(20)31142-9. [...] - Science brief: Community use of masks to control the spread of SARS-CoV-2. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/masking-science-sars-cov2.html. Accessed Jan. 10, 2022.