"The surgical mask blocked about 60% of .03 micron particles and over 90% of 1 micron and 2.5 micron particles."
"in one study, researchers tested particles down to .007 microns (even smaller than viruses) and found that a simple surgical mask blocked 80%."
"... it’s downright surprising that surgical masks are just as effective [as N95 masks]! Maybe virus particles are actually easy to capture because they fly on water droplets.
https://smartairfilters.com/en/blog/n95-mask-surgical-prevent-transmission-coronavirus/?rel=1