It’s simple science really. The corona virus is .12 microns in diameter and the n95 mask’s (AKA face mask) filter down to .30 , which is more than double the size of the virus.
So what good do the masks do?

>N95 mask packaging has a label or verbiage indicating protection down to 0.3 microns. Microns are small
– 1 millionth of a meter. Pollen particles are often 10 microns or bigger. Bacteria are often about 1
micron. COVID19 has a diameter of approximately 60–140 nm or 0.06 to 1.4 microns.

>Particles under 0.3 microns have so little mass the actually bounce around like pinballs when they
hit gas molecules, so they move in random zigzag patterns. This is known as Brownian Motion

Yet /sci/ thinks that masks do "work" despite the scientific evidence. Merely googling evidence to support your viewpoint is affirming the consequent. Just goes to show how many leftists actually browse this board as opposed to real scientists like myself.

SOURCE: https://www.sphosp.org/wp-content/uploads/2020/04/Letter-in-response-to-N-95-use-RA-Final.pdf