It looks to me like masks are not very effective. The subjects in these trials wore their masks in perfect form and many effectiveness ratings are still in the 20's and 30's!
https://www.epa.gov/sciencematters/epa-researchers-test-effectiveness-face-masks-disinfection-methods-against-covid-19
https://www.epa.gov/sciencematters/epa-researchers-test-effectiveness-face-masks-disinfection-methods-against-covid-19
It looks to me like masks are not very effective. The subjects in these trials wore their masks in perfect form and many effectiveness ratings are still in the 20's and 30's!
https://www.epa.gov/sciencematters/epa-researchers-test-effectiveness-face-masks-disinfection-methods-against-covid-19