On COVID-19 and catching it from people just "talking or breathing: Yes, there have been incidents that make it seem that this is sometimes the case. However, what's going on is likely not the kind of "aerosol" that people talk about with some diseases. ...

There are some viruses that linger in the air as aerosols after all droplets have dried out and can last, and be infectious, that way for an extended period. However, I don't think this is true of COVID-19, because true aerosol viruses--like measles--are just HUGELY infectious.…

Measles has an R0 value in double digits. If someone walks through a room with measles, everyone in that room that isn't immune to measles, gets measles.

And that's not the case with COVID-19. The R value is somewhere between 2 and 3, which is reflected in the growth rate. ...

It's probably true that you can get COVID-19 from talking / breathing, but it's likely the source is still droplets. Small droplets. So ... don't stand closer than 6' to someone, even if they're not coughing. And everyone wear a mask. Please.

Oh yeah, and I should end this thread with the reminder I try to pass along frequently -- I have degrees in geology, biology, and information science, but unless you happen to be a member of Polyodontidae, I'm no expert (and if you are... wow, congrats on learning Twitter).