micky presented the following explanation :
In alt.home.repair, on Sat, 17 Oct 2020 20:59:29 -0700, Bob F
wrote:

[...]

N95's are "respirators". They are supposed to seal to the face very
well. The next level, the KN95's do not, although they are better than
the "surgical masks".

Some ads for KN95 refer to FDA registration, but for pollen etc. Does
that mean there is registration for viruses but they didnt' manage to
get it, or does it mean that no mask is certifed by the FDA for viruses?

Some information he

https://smartairfilters.com/en/blog/...nd-kn95-masks/