Here’s one more behavior to be hyper-aware of in order to prevent coronavirus transmission: what you do after you use the toilet.
Scientists have found that in addition to clearing out whatever business you’ve left behind, flushing a toilet can generate a cloud of aerosol droplets that rises nearly three feet. Those droplets may linger in the air long enough to be inhaled by a shared toilet’s next user, or land on surfaces in the bathroom.
This toilet plume isn’t just gross. In simulations, it can carry infectious coronavirus particles that are already present in the surrounding air or recently shed in a person’s stool. The research, published Tuesday in the journal Physics of Fluids, adds to growing evidence that the coronavirus can be passed not only through respiratory droplets, but through virus-laden feces, too.
And while it remains unknown whether public or shared toilets are a common point of transmission of the virus, the research highlights the need during a pandemic to rethink some of the common spaces people share.
“The aerosols generated by toilets are something that we’ve kind of known about for a while, but many people have taken for granted,” said Joshua L. Santarpia, a professor of pathology and microbiology at the University of Nebraska Medical Center who was not involved in the research. “This study adds a lot of the evidence that everyone needs in order to take better action.”
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Typically, the coronavirus is most at home in cells in the lungs and upper respiratory tract. But studies have found it can also dock to cell receptors in the small intestine. Patients have been reported to experience diarrhea, nausea and vomiting among other symptoms.
And researchers have found viable virus particles in patients’ feces, as well as traces of viral RNA on toilet bowls and sinks in their hospital isolation rooms, although experiments in the lab have suggested that material may be less likely to be infectious compared with virus that is coughed out.
A computer simulation of the toilet flushing mechanism showed that when water pours into the toilet and generates a vortex, it displaces air in the bowl. These vortices move upward and the centrifugal force pushes out about 6,000 tiny droplets and even tinier aerosol particles.
Depending on the number of inlets in the toilet, flushing can force anywhere from 40 to 60 percent of the produced aerosols high above the seat.
“It’s very alarming,” said Ji-Xiang Wang, who studies fluid dynamics at Yangzhou University and was a co-author of the study.
It’s virtually impossible to keep bathrooms sanitized all the time, and sharing a toilet may be unavoidable for family members, even when one person is sick and isolating in a separate room at home, Dr. Wang said.
As cities around the world navigate the reopening of restaurants, offices and other businesses, more and more people will also need to use public or shared restrooms. But while diners can be moved outdoors and employees spaced out, people may find it harder to practice social distancing in small bathrooms.
Aerosolized particles may still linger in single-use toilets, and bathrooms are frequently poorly ventilated spaces, which can increase the risk of exposure to infection. Users also have to consider risks from high-touch surfaces, like doorknobs and faucets.
Experience with other coronaviruses shows how quickly the fecal-oral route can lead to spread of disease. In March 2003, more than 300 people living in the Amoy Gardens apartment complex in Hong Kong got infected with the original SARS coronavirus because infectious fecal aerosols spread through faulty plumbing and ventilation systems.
While Dr. Wang acknowledged that scientists had yet to look at toilet aerosols in real-world situations involving the new coronavirus, other research has shown that viral RNA was found in shared toilet areas at one hospital in Wuhan, China.
But researchers do not know how much infectious virus is in aerosols or whether people with more severe cases of Covid-19 shed more virus than patients with milder illness, he said.
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Updated June 16, 2020
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What is pandemic paid leave?
The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.
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Does asymptomatic transmission of Covid-19 happen?
So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.
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What’s the risk of catching coronavirus from a surface?
Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks.
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How does blood type influence coronavirus?
A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.
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How many people have lost their jobs due to coronavirus in the U.S.?
The unemployment rate fell to 13.3 percent in May, the Labor Department said on June 5, an unexpected improvement in the nation’s job market as hiring rebounded faster than economists expected. Economists had forecast the unemployment rate to increase to as much as 20 percent, after it hit 14.7 percent in April, which was the highest since the government began keeping official statistics after World War II. But the unemployment rate dipped instead, with employers adding 2.5 million jobs, after more than 20 million jobs were lost in April.
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Will protests set off a second viral wave of coronavirus?
Mass protests against police brutality that have brought thousands of people onto the streets in cities across America are raising the specter of new coronavirus outbreaks, prompting political leaders, physicians and public health experts to warn that the crowds could cause a surge in cases. While many political leaders affirmed the right of protesters to express themselves, they urged the demonstrators to wear face masks and maintain social distancing, both to protect themselves and to prevent further community spread of the virus. Some infectious disease experts were reassured by the fact that the protests were held outdoors, saying the open air settings could mitigate the risk of transmission.
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My state is reopening. Is it safe to go out?
States are reopening bit by bit. This means that more public spaces are available for use and more and more businesses are being allowed to open again. The federal government is largely leaving the decision up to states, and some state leaders are leaving the decision up to local authorities. Even if you aren’t being told to stay at home, it’s still a good idea to limit trips outside and your interaction with other people.
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What are the symptoms of coronavirus?
Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.
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How can I protect myself while flying?
If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.)
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Should I wear a mask?
The C.D.C. has recommended that all Americans wear cloth masks if they go out in public. This is a shift in federal guidance reflecting new concerns that the coronavirus is being spread by infected people who have no symptoms. Until now, the C.D.C., like the W.H.O., has advised that ordinary people don’t need to wear masks unless they are sick and coughing. Part of the reason was to preserve medical-grade masks for health care workers who desperately need them at a time when they are in continuously short supply. Masks don’t replace hand washing and social distancing.
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What should I do if I feel sick?
If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.
Thankfully, people can also easily prevent the spread of infections from the toilet plume.
“Close the lid first and then trigger the flushing process,” Dr. Wang said, which he acknowledged isn’t always possible in public bathrooms.
You should also wash your hands frequently and thoroughly, especially if you’re using a shared restroom where the toilet doesn’t have a lid or the flush is automatically triggered on standing up. Avoid touching your face, and keep your mask on in the bathroom, which could prevent some exposure to the coronavirus.
Dr. Wang hopes the new research will help lead to improvements in bathroom design, including increased attention to contactless dispensers for soap and paper towels, and toilets that flush only after they have been covered with a lid.
Other experts are already considering indoor ultraviolet lights and automated disinfectant sprays that will zap the coronavirus and relieve some of the pressure on keeping public toilets clean.
And Dr. Santarpia said that the Dr. Wang’s study could point to a way of monitoring coronavirus clusters.
“You could simply monitor samples from a shared bathroom on a daily basis,” he said. “And if something were to come up positive, you could then go look at everyone who was there and who they had contact with, rather than testing everybody all the time.”
