Poop really might pose a threat, according to researchers.
Right now, coronavirus lockdowns are lifting, and you’re probably venturing into public spaces again. But what do you do when you have to go to the bathroom? Is it safe to use a public restroom, or could you pick up COVID-19 there? Because let’s face it, it’s pretty difficult to socially distance in a small (and most likely poorly ventilated) bathroom.
A new study sheds light on the potential dangers of public restrooms. The study, published June 15 in Physics of Fluids, found that flushing a toilet can create a cloud of aerosol droplets (called a “toilet plume”) reaching a height of almost three feet. This is an issue in relation to the new coronavirus, because those droplets may stay in the air long enough to be inhaled by the next user of the toilet, or land on surfaces in the bathroom. If the droplets contain infectious coronavirus particles, this increases the risk that the person who inhaled them could contract COVID-19.
Using computers to simulate a toilet flushing, the researchers found that when water flows into the bowl, it creates a vortex and disturbs the airflow. This results in a centrifugal force, which pushes thousands of tiny droplets and aerosol particles into the air. The researchers say a single flush can drive between 40% and 60% of the aerosols into the air above the seat.
Although the coronavirus is most likely to attach to cells in the lungs and upper respiratory tract, it can also target the small intestine, causing diarrhea, nausea, and vomiting alongside more common COVID-19 symptoms. Studies have found evidence of COVID-19 genetic material in fecal matter, but more work is needed to confirm if the virus can be spread through poop.
Still, no study has told us how much infectious virus is in aerosols, nor looked at toilet aerosols in real-life situations—although research published April 27 in the journal Nature showed that viral RNA from the coronavirus was detected in shared toilet areas at one hospital in Wuhan, China.
“There haven’t been any reported cases of transmission of the coronavirus from toilet flushing,” infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland, tells Health. However, there has been one report out of Hong Kong about leaky pipes possibly being a route of fecal spread to another individual, he says.
Dr. Adalja says it may be prudent to close the toilet lid before flushing to protect others in the restroom. When it comes to dispersing virus-containing droplets on surfaces, he agrees that there is a risk, but he says he wouldn’t hesitate to use a public restroom. Public health expert Carol A. Winner, MPH, who has directed several federally funded community health-based initiatives and founded the Give Space movement in 2017, is a little more cautious.
“A public restroom is a Petri dish,” she tells Health. “If you have no alternative other than using a public restroom, use it. Best advice is the same as when we were kids—’Everyone go to the bathroom before we get in the car!’”
Toilet plume aside, Winner says the steel surfaces, doorknobs, and toilet handles in a public restroom pose the greatest risk. But if you have to go, she advises wearing a face mask the entire time you’re in the restroom, closing the lid via a tissue in your hand, using your foot on the handle to flush, and turning your face away from the toilet bowl during the flush. After you wash your hands—“the most important health behavior”—use a paper towel to turn the faucet off, she says.
“Remember that the door handle is often a steel surface, which may harbor active virus for up to three days, so don’t discard the paper towel until you’ve opened the restroom door on your way out,” Winner adds.
The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it’s possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.
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