CIDRAP (Center for Infectious Disease Research and Policy) at University of Minnesota has doubts, saying advisories on masks may not be based on sound data:
Johns Hopkins School of Public Health suggests it depends on what kind of mask:
However these doubts do not appear to question the efficacy of wearing a mask to protect others from virus-bearing droplets the wearer might emit.
So Joan's COVID-19 Blog will continue to urge wearing a mask in order to protect others.
My own view at this time is based upon the Precautionary Principle: Since wearing a mask is not onerous or dangerous, and since it could be helpful in slowing or stopping COVID-19 virus transmission, why not? https://en.wikipedia.org/wiki/Precautionary_principle
Whether or not a mask protects you from what others may emit, a covering over your nose and mouth can block droplets of fluid you may emit as you cough, sneeze talk or even breathe!
These droplets may hold COVID-19 virus which you may be carrying even though you may not have any symptoms, thus infecting others.
Given this information, and since wearing a mask is not dangerous or even burdensome for me, and since it could protect others around me, and could possibly even give me some degree of protection, I'll continue to wear a mask whenever I leave my apartment, while still maintaining social distancing and other hygienic measures (washing hands, etc.)