It's not only this reason. Even N95 masks are rated only to .3 micron. COVID-19 is .1 micron. It will prevent droplets from those already infected but I don't see how it would help in the healthy much. Maybe it slows down the air breathing out? But I don't see that helping a lot.
Arh. I see it now. When ever Mask is mentioned in the context of CJK, it meant medical mask with 95% PFE, VFE and BVE mask. Stopping size of 0.1 Micron.
Sorry I wasn't being clear enough. We knew very early on N95 doesn't work.
