From Chicago area food market store email (italics and bold added):
Shop and Save Market firstname.lastname@example.org Wed 4/22/2020 3:00 PM Face Mask Required Effective April 22nd, Dear Customers, We respectfully request that you wear a protective face covering when shopping with us. For your and our safety & protection. Mask, Homemade Mask, Bandana or Scarf.
For your safety & protection
If a person is surrounded by SARS-CoV-2 virus in a given place, otherwise a protective face covering for you is not needed, viruses are disseminated equally around the head and neck areas at least. Even when virus’s carrier sneezes in close proximity at the person wearing a bandana.
The droplet nuclei (containing the viable viruses, in sneezing 40 million, in coughing only 5 million) do not have any knowledge where the “infection gates” (nose, mouth, eye conjunctive) are. Droplet nuclei land indiscriminately on every place. However, a mask, bandana or scarf provide them conditions in maintaining their comfortable dwelling by warm and wet person’s breath. Although the forehead or the neck might be sweaty, at these places and especially on the cloth viruses are less viable by losing their water surrounding.
The protective mask becomes a hub for viable viruses. The face cover should be treated as biohazard material. Are these masks taken off according to infectious epidemiology rules avoiding contamination of hands, face, and cloth? Are they disposable? More than likely not. How are they discarded? And numerous additional epidemiology questions.
For our safety & protection
Apparently, this is about preventing SARS-CoV-2 virus contamination the indoor space. Face covering to protect others from the potential carrier of viruses could be rational if a symptomatic people come in droves to the enclosed public spaces and sneeze and cough out their infectious material. This is very much questionable now. Asymptomatic viruses’ carriers distribute them without sneezing and coughing. Workers, who perform in-person jobs, now have separating from public plastic screens and use non-medical grade face coverings.
Nasopharyngeal area is one of the first lines of defense in the fight with a virus, which includes the initial cellular immunologic response. This defensive zone is the product and gift of humans evolution. The face covering does not contribute to its effective function. I know this as a person who worked many hours using a protective personal equipment mask.
In contrast to (PPE), which is a necessity under certain conditions for medical and other professionals, in my definite believe, the face covering in public space indoors and definitely outdoors is not only unnecessary but wrong under COVID-19 epidemic.