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not sure if they're banned or not, they're not recommended because the valve lets you exhale unfiltered air, which is rather pointless for covid protection. For
by aulin 5y ago
not sure if they're banned or not, they're not recommended because the valve lets you exhale unfiltered air, which is rather pointless for covid protection. For particulate filtering they're perfect though.
- seanmcdirmid 5y agoThey are banned on planes and such. You can’t even really layer them since the second mask under would break the seal. The theories on mask wearing are different there and here, or perhaps there is just more flexibility. Since China has such a low infection rate, the difference between an in-coming or out-going filter probably isn’t going to matter much.
- jerlam 5y agoRecent studies show that valved respirators are actually better than or equivalent to surgical and cloth masks for source control: https://www.cdc.gov/niosh/docs/2021-107/default.html https://www.cdc.gov/niosh/docs/2021-107/default.html However, the "valves bad" mantra has been repeated so long and so strongly that it is unlikely there will be any official guideline change.