Important question: After you do your business and you’re ready to flush, do you close the toilet lid before you do? Or flush with the lid open?

The first option is correct (and we’re about to tell you why), and yet about 60 percent of respondents to a Scrubbing Bubbles survey say they don’t shut the lid before they flush. Jaw drop, much?

It’s pretty crazy that so many people don’t shut the lid of the toilet before flushing considering this habit has been in discussion since 1975 when germ expert Dr. Charles Gerba brought it our attention in a famous study published in Applied Microbiology.

The study found that when you don’t close the lid, E. coli bacteria flies up from the water (sometimes it can get as high as 15 feet!), which can linger in the air for up to six hours!

“You get a good spray out of the toilet area,” Dr. Gerba said. “When droplets come out of the toilet, it looks like the Fourth of July.”

And when those droplets finally settle down, guess where it lands? The floor, the sink, the mirror, all over your bathroom. It also can land on whatever you keep in the bathroom that you use pretty frequently—your toothbrush, your contact lenses, your hand towels. Everyone who lives with you and uses that bathroom or those items is now exposed to these germs.

Each time you flush the toilet, “an aerosol is created due to the rush of water into the bowl,” said Jason “The Germ Guy” Tetro, a visiting scientist at the University of Guelph in Canada and author of The Germ Files: The Surprising Way Microbes Can Improve Health and Life (and How to Protect Yourself From the Bad Ones). “When this happens, any microbes deposited into said toilet may be sent into the surrounding environment.”

If you need more incentive to close the lid, a 2012 study published in the Journal of Hospital Infection found that when the lid was left up instead of down, there were 12 times as much diarrhea-inducing bacterium Clostridium difficile in the air. Excuse us while we gag.

If you’re wondering if air droplets are harmful when in the air, the answer is yes. A 2013 study published in the American Journal of Infection Control found that not closing the lid when you flush—or as the researchers call it, “toilet plume,” can result in the transmission of infectious diseases.

Just some of the diseases you might catch from a toilet plume? Norovirus, SARS, and COVID-19. Remember, you’re flushing anything from urine to waste to vomit.

According to Alvin Lai, a key researcher for a study done by the City University of Hong Kong, “covering the toilet lid while flushing is definitely essential, but it should not be considered a complete prevention.” He suggests cleaning bathrooms regularly with diluted bleach.

If you must use a public restroom during the coronavirus pandemic, here are some precautions you can take. First of all, don’t use the toilet right after someone else has used it – wait a few minutes. Wash your hands after you use the toilet, put the toilet seat down (if there is one) and flush the toilet with gloves or a paper towel.

Even if you have a low-flow toilet, while it might help with the spewing droplets a little, a study published in Aerosol Science and Technology showed that less water doesn’t always mean it sprays less. “Even though you may be saving energy [with a low-flow model], best to expend a little arm energy and cover the toilet with the lid before you flush,” Tetro says.

So let’s end this in the same way we started: Do you close the lid or leave it up when you flush? It takes about one full second to close the lid, so we hope your answer changes if it was the latter! Is has always been important to close the toilet lid, but now it’s more important than ever.