Contrary to previous recommendations from the World Health Organization and CDC, new data suggests coronavirus may very likely be spread by just speaking or breathing someone else’s air, that is by aerosol, particles less than 5 micrometers. In addition, transmission by completely asymptomatic or minimally symptomatic infected persons occurs more frequently than previously suspected, perhaps accounting for over 20% of cases.
In a letter requested by the federal government on April 1, Dr. Harvey Fineberg of the National Academy of Sciences detailed the data, responding to the question whether the virus could be spread by conversation, in addition to sneeze/cough induced droplets, concluded: “currently available research supports the possibility that SARS-CoV-2 could be spread via bioaerosols generated directly by patient exhalation.”
In addition, recent laboratory data conducted at the federal lab in Hamilton Montana showed persistent aerosolization in a barrel at three hours, though in the real world the time may be shorter.
Dr. Fineberg told a reporter he was going to start wearing a bandana when he goes to the store. We don’t know how much protection bandanas or homemade masks offer, but they are likely to prevent that aerosol spread to some degree. Though not a substitute for social distancing, and we certainly should not yet issue medical/surgical masks to the general public since it would deplete our limited supply for healthcare workers, homemade masks and bandanas can have two beneficial effects. First, they can decrease the likelihood you will get infected by someone asymptomatic, and secondly, they can prevent spread to essential workers. So we should now start wearing homemade masks when we go must go out, in addition to social distancing, and essential workers should mask to prevent them from becoming infected, even though the actual efficacy of these changes aren’t precisely known.
So stay home and sew at least two masks — one for you and one to give to an essential worker out there taking risks to supply us with our critical needs. It looks like this will stop some cases, and until we can do community-wide testing to isolate cases will likely offer some protection to us, and our essential workers.