This seems like something that should be true, but I think I remember seeing a Mythbusters episode where they decided it didn’t make a difference. That show was more about entertainment than science, so I wondered if there was a more rigorous study done? I’ve definitely seen splashes of water(?) come out from flushes so that alone seems to argue for closing lids.
I remember watching a video where they added some liquid visible with UV to the water and flushed, there were droplets everywhere including the tester’s face.
It’s not a study but it’s enough to make me close the lid, especially when my toothbrush is in the same room.
I saw the same or a very similar video.
Someone once tried to argue against it by saying it still got the droplets in the air with the lid closed so there’s no point. My counterargument was that it still contained a lot of the droplets by closing it and that it’s the most minor of inconveniences to close it so you should just do it anyways.
Ah the ol “it’s not 100% effective and guaranteed to work so you should actually do nothing about it” argument…a true classic in any situation
Seriously though…I never even considered all the splashing and I’m a grown ass adult :/ happily my and my daughters toothbrush live in the kitchen