Let me emphasis the: will NOT provide ANY protection against COVID-19 or other virus or contaminants.
Read this article. A lot of links and explanations
Or talk to physicist
https://pubs.acs.org/doi/10.1021/acsnano.0c05025
Brownian motion means masks are going to capture particles. You are trying to reduce the viral load.
“masks are going to capture particles. You are trying to reduce the viral load.”
The Border Patrol agents are going to capture alien invaders.
We are trying to reduce the alien load.
As time passes, ever more aliens get past the Border Patrol agents.
Surgical grade masks may work well for elderly folks snapping up groceries in 15 minutes each week.
For children attending school 190 days a year for six to seven hours masks are not going to be a game changer.
Proper hygiene and a healthy immune system will protect you better than a cloth/paper mask. The surgical mask boxes literally used to have a warning that they didn't work against a virus. Don't know if the still do, or not.
How about the viral load of the person wearing the mask?
Let me emphasis the: will NOT provide ANY protection against COVID-19 or other virus or contaminants.
For a virus with a relatively low inherent R0 factor, like the first COVID-19 variant, cutting the effective R factor in half is helpful since 50% of 2.0 is 1.0 which would in theory stop the spread of the epidemic statistically speaking. For a virus with a higher R0 factor, like the Delta variant of COVID-19 with its R0 in the range of 6.0, cutting that in half still results in an effective R higher than the original variant.
In terms of personal protection in any situation it is true that something might be better than nothing. But assuming a 50% effective filter is going to make a difference is like wearing body armor on 1/2 of your torso. It probably helps, but isn't worth relying on.