The transmission of COVID is arguably still and unanswered question. The current focus is on aerosol transmission. However as we have noted many times the science behind this is limited and quite complex. Aerosol transmission has two dimensions. First the physics of the problem, aerosols are temporal-spatial random fields. Thus their analysis and prediction is at best estimates. Second, and even more importantly is the mechanism of viral transport. 30nm virions somehow get embedded in the aerosol, say 100nm in diameter and that aerosol goes from A to B and must attach itself, most likely in the nasal passage.
Some academic has opined in the NY Times regarding this process. Lots of words but no answers. The author notes:
It took a long time for air cleaning to be recognized as a powerful tool for reducing the risk of Covid-19 transmission, and it should be embraced more thoroughly during this pandemic and to reduce flu cases. Ventilation and filtration are two proven techniques for physically removing viruses from the air, so that people are exposed to fewer of them....There are some simple ways to improve ventilation, like opening windows and doors. A recent small study, which has not yet been peer-reviewed, showed that the amount of coronavirus in the air was substantially lowered when ventilation was significantly increased by running an exhaust fan that removed stale air from a room, pulling in outside air through an open window. Other effective options can require more effort. Ultraviolet treatment is another approach used in hospitals to kill viruses in the air. This technique could be more broadly applied in crowded public areas, although it must be properly installed to be effective and avoid the potential for harm.
Suggesting solutions without understanding the problem becomes some religious artifact. UV is interesting but it at best covers things on the surface. A new person may reintroduce the pathogen as soon as they enter. Masks are also problematic. In examining the many in NYC, half have their noses uncovered. Thus the mask is useless. Also we really do not know how many aerosols get around a mask.
It will take a few years of real study to determine the best way to deal with this. Vaccines work for almost all. At this point they are our best bet.
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