This is very informative; an excerpt:
The studies suggesting that [the new coronavirus] can be aerosolized are only preliminary, and other research contradicts it, finding no aerosolized coronavirus particles in the hospital rooms of Covid-19 patients.
The weight of the evidence suggests that the new coronavirus can exist as an aerosol — a physics term meaning a liquid or solid (the virus) suspended in a gas (like air) — only under very limited conditions, and that this transmission route is not driving the pandemic....
In droplet form, the coronavirus is airborne for a few seconds after someone sneezes or coughs. It’s able to travel only a short distance before gravitational forces pull it down....
An aerosol is a wholly different physical state: Particles are held in the air by physical and chemical forces. Fog is an aerosol; water droplets are suspended in air. The suspended particles remain for hours or more, depending on factors such as heat and humidity. If virus particles, probably on droplets of mucus or saliva, can be suspended in air for more than a few seconds, as the measles virus can, then anyone passing through that pathogenic cloud could become infected.
There are strong reasons to doubt that the new coronavirus has anything close to that capability.
“If it could easily exist as an aerosol, we would be seeing much greater levels of transmission,” said epidemiologist Michael LeVasseur of Drexel University. “And we would be seeing a different pattern in who’s getting infected. With droplet spread, it’s mostly to close contacts. But if a virus easily exists as an aerosol, you could get it from people you share an elevator with.”
According to the Centers for Disease Control and Prevention, that is not happening. Earlier this month, CDC scientists reported that the rate of symptomatic infection among a patient’s household members was 10.5%. The rate among other close contacts was 0.45%. In the case of one particular patient, none of his five household members, although continuously exposed to the patient during the time he was isolated at home, tested positive for the virus.
Even if the virus infects only a small fraction of those who come into contact with it, the extremely low rate among close contacts and the absence of infections in some household members of patients suggests that it rarely exists as an aerosol in most real-world situations.
“It’s more evidence that [Covid-19] is predominantly spread through droplets and not as an aerosol,” LeVasseur said....
The article has more interesting details so is worth reading in its entirety.
(Thanks to David Ozonoff for the pointer.)
