We know that wearing a mask outside health care facilities offers little, if any, protection from infection. 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). The chance of catching Covid-19 from a passing interaction in a public space is therefore minimal. In many cases, the desire for widespread masking is a reflexive reaction to anxiety over the pandemic.
Michael Klompas, M.D., M.P.H., Charles A. Morris, M.D., et al. “Universal Masking in Hospitals in the Covid-19 Era.” N Engl J Med 2020; 382:e63 DOI: 10.1056/NEJMp2006372