This may be important enough to clarify, at least for some people in some settings.
Surgical masks are reasonably good protection against droplets (from sneezing, etc.) but they can't protect against airborne virus particles. For one thing, they don't form a seal. They are best used by people who actually have (or might have) transmissible disease, to provide some measure of protection for
others.
N95 respirators (the designation indicates that they block at least 95% of 0.3 micron particles) are much more effective than surgical masks in protecting the
wearer. However, that's only true when they are properly fitted, which is seldom the case when they are selected and worn by untrained personnel. And if you've ever worn one for very long, you know that they are very uncomfortable.
Most transmission of "airborne" virus disease is actually the result of contact, e.g., touching a contaminated object/person/surface and subsequently touching nose/eyes/mouth.
The lesson from all of this is that, if you are in a situation where the risk of infection is high, you should be masked, gowned, wear goggles, have a properly-fitted respirator and be trained in infection-control practices. Measures less stringent that those
might be helpful -- if you're lucky -- but it's foolish to rely upon them if the risk is high.
If you are interested in "official" guidance, the US Centers for Disease Control provide some here:
https://www.cdc.gov/niosh/npptl/topi...espsource.html