This is a good time to bring up "toilet plume."
There’s a hidden danger lurking in your bathroom, and the only way to protect yourself from it is to drop that toilet lid. We’re talking about a “toilet plume.” The nastiness doesn’t end after you flush it down. Leaving that lid up has aftereffects. A germ plume of the funk-infused toilet water can rise up to fifteen feet, infecting everything in its reach with the worst kind of bacteria. It’s an easy thing to do, so help yourself – and close that lid.
Source: Men’s Health