Dog owners know all too well about the problems of shedding in the car, but another kind of shedding presents an even stickier problem: people shedding SARS-CoV-2, the virus that causes COVID-19. Every time we cough or sneeze, we spew a whole slew of aerosols into the air. Some are big enough that you can see them ejected out of someone’s mouth or nose. Some are “big” in an aerosol physics sense but still invisible to the naked eye, and those settle onto surfaces rather quickly. And some are small enough that they can float around in the air.