The CDC, today, issued guidelines for reopening offices that ignore medical guidance regarding masks. The latest medical guidance, according to May 21 article in the New England Journal of Medicine reported here, says: Public health authorities define a significant exposure to Covid-19 as face-to-face contact within 6 feet with a patient with symptomatic Covid-19 that is sustained for at least a few minutes (and some say more than 10 minutes or even 30 minutes).