I wonder if this has anything to do with the N-95 mask and not being able to block the virus?
I am not sure, but if the virus is 0.2 microns.
And the N-95 mask blocks 90% of particles bigger than 0.3 microns.
My guess is it may block less than 50% of particles as small as 0.2 micron.
I do need to look into this better before I can confirm this statement.
Lots of studies looking at mask materials have been done. Each study fires dirt at the mark. No mask stops it all. However it's only about making you feel better anyway. Non of them masks are suitable for even a saw mill. There is no seal round your face. You can pull in loads of unfiltered air. They're just a splash guard. That is why there is no rush to provide more. People can form community groups and feel they're helping, but it's just a joke. If you work with the ill, you get ill. It's the job. There are no air feed visors at that level of care. $150 buys one though.