COVID-19: Mayo Clinic expert answers questions about masks ...
Apr 06, 2020·What's the difference between cloth masks and medical masks, such as an N95 mask? A. The idea behind an N95 mask is it has a filtering ability down to, and actually below, the size of SARS-CoV-2, the virus that causes COVID-19. So the coronavirus is about 0.12 microns in diameter and N95 (masks) protect down to 0.1 microns, with 95% efficiency ...