[Fungi]

The size of corona virus is 125 nanometers, that is 125 one billionths of a millimeter. No mask can prevent transmission on that scale.

[Ann Archy]

MASKS ARE NOT HEALTHY!

[HighSierra5]

Duct tape.

[DuncanWaring]

125 nanometers, that is 125 one billionths of a millimeter.

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125 nanometers, that is 125 one billionths of a METER, not millimeter.

[TexasFreeper2009]

something smells about all of this.

put people out of work, pay them do to nothing, take away their sports and other distractions, make wearing a mask everyday and then keep the police from stopping the rioters wearing them, and arrest anyone who tries to stand up to the rioters.

[Svartalfiar]

The size of corona virus is 125 nanometers, that is 125 one billionths of a millimeter. No mask can prevent transmission on that scale.

True, but virus particles aren't just freefloating around. An infected person is generally shedding them in their breath/saliva. N95 masks are rated to stop 95% of particles .3microns or larger, and from testing they're generally that effective down to .1 to .2 microns. (Note 1 micron = 1 micrometer = 1000 nanometers.) Most of your aerosolized droplets in your breath are .1-.5 microns, with many larger droplets as well.

I have the full data somewhere in a week-old post. But most N95 masks (the white round dust masks you get for sanding/dust) will stop a good portion of the virus, although plenty is still getting through and more than enough to infect someone. BUT if they aren't fitted/fully sealed, any air leakage drops their effectiveness down to 20-30%. Likewise, when "mask required" is satisfied by a bandanna or scarf, you are getting almost no protection - all those stop is snot and spit if someone coughs or sneezes.