Leaving the toilet seat up isn’t just a common annoyance in households the world over, it’s also unsanitary as it allows a cloud of bacteria from flushing to settle on surfaces in the bathroom.
Charles Gerba, a microbiologist from the University of Arizona, explained to realtor.com that the problems with leaving the seat up have to do with something called the aerosol effect.
“You get a good spray out of the toilet area,” Gerba said. “When droplets come out of the toilet, it looks like the Fourth of July.”
After flushing, the force of the water flooding the toilet bowl can create a spray that splashes out of the bowl and with it a cloud of bacteria that can spread throughout the bathroom.
The spray of bacteria can go as high as 10 inches above the toilet and remain in the air for an hour or more.
According to the Daily Mail, this bacteria can then settle over the sink, bathtub, and walls.
On average, a person flushes around six times a day adding up to 2,190 flushes a year. Unfortunately, given how much bacteria is eliminated through human waste, no matter how much you flush many of those germs stay behind.
Leaving the seat up not only provides an outlet for that bacteria to escape but it also increases the risk of flu and norovirus spreading to others.
“It is a good idea to lower the seat, especially if the bathroom is used by multiple people,” Philip Tierno, a microbiologist previously told Tech Insider.
One study conducted by researchers from the University of Oklahoma Health Science Center examined whether the aerosol effect differed based on the type of toilet involved.
The researchers tested aerosol generation from high-efficiency toilets, pressure-assisted high-efficiency toilets and tankless toilets that use a flushometer.
While the results showed that low flow toilets create less of a cloud of bacteria, the aerosol effect is still present.
By Kay Vandette, Earth.com Staff Writer