But before aerosols can get far, they have to travel through nearby air, which means they’re a danger at close range as well. And especially since, like cigarette smoke, aerosols are more concentrated near the infected person (or smoker) and dilute in the air as they move away .
A peer-reviewed study by scientists at the University of Hong Kong and Zhejiang University in Hangzhou, China, published in the journal Building and Environment in June concluded: “The smaller the expired droplets are , the greater the short-haul air route. ”
So what does all of this mean exactly, practically?
Can you walk into an empty room and contract the virus if an infected person, now gone, was there before you? Maybe, but probably only if the room is small and stuffy.
Can the virus move up and down buildings via air ducts or pipes? Perhaps, although it has not been established.
More likely, research suggests that aerosols are important in extremely mundane scenarios.
Take the case of a restaurant in Guangzhou, southern China, earlier this year, in which a SARS-CoV-2-infected diner at a table spread the virus to a total of nine people seated. at their table and at two other tables. .
Yuguo Li, an engineering professor at the University of Hong Kong, and his colleagues analyzed video footage of the restaurant and in a pre-post (not peer reviewed) published in April, found no evidence of close contact between the guests.
The droplets cannot explain the transmission in this case, at least not among people at the tables other than those of the infected person: the droplets would have fallen to the ground before reaching those tables.