Sure they work--bandits have been using them to rob honest folks for years.
For stopping covid? Only in your dreams, according to the Annals of Internal Medicine.
About that mask recommendation...
www.medpagetoday.com
The authors pointed to earlier research showing particles 0.04 to 0.2 μm "can penetrate surgical masks." For the coronavirus responsible for SARS, particles were estimated to be within that range at 0.08 to 0.14 μm, they said.
"Assuming that SARS-CoV-2 has a similar size, surgical masks are unlikely to effectively filter this virus," they wrote. "The size and concentrations of SARS-CoV-2 in aerosols generated during coughing are unknown."
Try again, moron.