A movie that understands 'the reason why you should not flush with the lid of the toilet open' in one shot

When using the toilet at a restaurant, etc., many people have seen a notice that says, ``Please close the lid and flush the toilet to prevent infectious diseases.'' When you see a movie that visualizes the particles that blow up from the toilet when flushing the toilet with laser light, you can intuitively understand why the toilet should not be flushed without the lid.

Commercial toilets emit energetic and rapidly spreading aerosol plumes | Scientific Reports


CU scientists shine light on what comes up when you flush | CU Boulder Today | University of Colorado Boulder

So far, research results have been reported showing that tens of thousands of aerosols are emitted from flush toilets, but the speed at which fine particles are ejected from the toilet bowl and the behavior of water droplets that roll up are unknown.

Therefore, a team led by John Crimaldi, who is studying engineering at the University of California, Boulder, is investigating how pathogens that are transmitted through excrement, such as new coronavirus infections and norovirus, are spread by flush toilets. To investigate this, we conducted an experiment to observe the behavior of aerosol particles with laser light.

The state of the experiment can be seen from the following movie.

Shining a light on what comes up when you flush-YouTube

In a dark room, there is a type of flush toilet that does not have a lid, which is common in public toilets in North America. The green light streak is a laser for detecting particulates.

When I flushed the toilet, countless water droplets sprang up from the toilet bowl.

Analysis revealed that the particles generated when flushing the toilet had a velocity of 2 meters per second and reached a height of 1.5 meters above the seat within 8 seconds. Also, while large water droplets fell in seconds, fine particles on the order of a few microns remained suspended in the air for minutes or longer.

In other words, if you flush the toilet without closing the lid, the particles will rise to the height of your face in just a few seconds and will continue to float for a long time.

Also, in this experiment, no solids or toilet paper were put in the toilet bowl, and no people moved near the toilet bowl, but the research team pointed out that such factors could worsen the experimental results. doing.

``We thought that the aerosol particles just floated up, but when we experimented, they popped out like rockets,'' Crimaldi said. It's easy to do, but if you watch this video that visualizes the particles when you flush the toilet, you'll never think that way again.'

in Science,   Video, Posted by log1l_ks