N95 is rated down to .3 microns, and studies show it prevents approx 95% of covid, if, as you point out, it's fitted correctly. Some like to point out covid is smaller then that, but it does not float around as a single virus, but in droplets far larger then that.
While some covid can make it through, what an industrial hygienist may not be aware of is that what's called the "inoculate dose" which means the actual amount exposed to is a major variable to not just if you get infected, but how sick you may get. Hence, reducing the inoculate dose still has big benefits. Combined with social distancing, it drops even further.
The N95, fitted correctly, is far better than nothing. The rest are just slightly better than nothing, but sill better then nothing. A good article on the science/physics of it:
https://www.wired.com/story/the-phys...n95-face-mask/
Studies of interest:
https://pubs.acs.org/doi/10.1021/acsnano.0c03252
https://www.thelancet.com/journals/l...142-9/fulltext
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7184463/
https://www.preprints.org/manuscript/202004.0203/v1
(1) My take personally is that under controlled conditions, masks are clearly a benefit to greatly reducing covid infection and spread, in the wild, where people don't fit them right, use them right, etc, etc, has shown to have minimal benefits, but will for the
individual does it right.
(2) The current strains are so infectious yet so much less pathogenic (the usual route for a respiratory virus) there's no way to avoid exposure and a low likelihood for serious complications and death, unless you have co morbidity that put you at high risk. At this point for most people, masks are a waste of time. What people should do, is focus on good health and innate immunity, cus they're going to get exposed one way or another at this point.
I'm not even gonna mention the vax issue as that will go no place fast.
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