It's hard to make water droplets that are even as small as a micron (1000 nm) unless you're actively trying to do it, and even then it's a pain. Water droplets are also relatively easy to catch on a filter as long as it's a type that will wet. Coughing and sneezing (and even talking) tend to produce droplets much larger than a micron, and virtually none smaller than 5 micron.

Most viruses don't last long outside the body, and it depends on conditions. Coronaviruses look pretty durable- as long as days on some surfaces, and on PPE, though some metals (copper, copper alloys like brass) seem to have antiviral properties. That there aren't planeloads of people running around with it suggest that it doesn't transmit that well through air.

FWIW, I'm flying transcon out of LAX tomorrow and not terribly worried about it. I keep a box of N95 masks at home for days when there are a lot of particulates in the air from fires, and they'll be staying in the box.