Consider the case of a restaurant in Guangzhou, southern China, at the beginning of the year, in which one diner infected with SARS-CoV-2 at one table spread the virus to a total of nine people seated at their table and two other tables.Yuguo Li, a professor of engineering at the University of Hong Kong, and colleagues analyzed video footage from the restaurant and in a preprint (not peer reviewed) published in April found no evidence of close contact between the diners.Droplets can’t account for transmission in this case, at least not among the people at the tables other than the infected person’s: The droplets would have fallen to the floor before reaching those tables.But the three tables were in a poorly ventilated section of the restaurant, and an air conditioning unit pushed air across them. Notably, too, no staff member and none of the other diners in the restaurant — including at two tables just beyond the air conditioner’s airstream — became infected.