So you've never been standing by the side of a road then, when a roadie, or group of them, come past huffing and puffing like steam trains - honking out of the saddle giving it a lung-busting effort to get up a gradient at speed rather than dropping right down into a low gear and spinning up? It doesn't take a genius to work out that the heavy breathing cyclists exhalations are going to carry further on the air than someone who just accepts that the climb is going to be slow, stays in the saddle, and gears down.
The virus doesn't bother me in the slightest, but I can see why some people don't want heavy breathing riders passing close by.