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Putting the toilet seat down BEFORE flushing could stop the spread of COVID-19

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Putting the toilet seat down after defecating and before flushing could help stop the spread of COVID-19, a study has found.

The coronavirus is hardy and can survive a trip through a human’s digestive system. It is often still present in faeces weeks after symptoms have stopped. 

Flushing stools kicks a cloud of infectious particles up to 3ft (one metre) above the water, due to turbulence created by the rapid flow of water, a study has found. 

Some particles are trapped by the bowl or the water, but in an uncovered toilet, up to 60 per cent of droplets escape above the seat.

Researchers say the virus could then either directly infect another person or settle on a nearby surface, such as a worktop or door handle. 

In order to combat this, scientists urge people using shared or public toilets to close the lid after concluding their business and before pulling the chain.  

Flushing stools kicks up a cloud of infectious particles up to 3ft (one metre) above the water due to turbulence created by the rapid flow of water, a study has found. Pictured, computer simulations showing the vortices (left)  created by a flushing toilet which transport particles (right)

Flushing stools kicks up a cloud of infectious particles up to 3ft (one metre) above the water due to turbulence created by the rapid flow of water, a study has found. Pictured, computer simulations showing the vortices (left)  created by a flushing toilet which transport particles (right)

In an uncovered toilet, up to 60 per cent of ejected droplets escape above the seat due to the turbulence from the flushing water (stock)

In an uncovered toilet, up to 60 per cent of ejected droplets escape above the seat due to the turbulence from the flushing water (stock)

Previous research has found SARS-CoV-2, the virus which causes COVID-19, can be transmitted via faecal particles. 

A study published last month in the Lancet identified virus particles in the excrement of COVID-19 patients nearly 5 weeks after the patients tested negative.

These particles were still viable and could cause faecal-oral transmission of the coronavirus, the researchers warned.   

Despite this, the general public is less aware of this potential route of transmission than they are other methods of infection. 

The coronavirus is hardy and can survive a trip through a human's digestive system and is still present in faeces, often for weeks after symptoms have stopped. Pictured, water level in a toilet before it is flushed, as seen in the researcher's computer simulations

The coronavirus is hardy and can survive a trip through a human’s digestive system and is still present in faeces, often for weeks after symptoms have stopped. Pictured, water level in a toilet before it is flushed, as seen in the researcher’s computer simulations 

Simulations showed that water cascading down the side of the ceramic hits the opposite side of the bowl and this creates vortices, similar to a tornado or whirlpool. This sends infectious droplets out of the toilet bowl. Pictured, the computer showing the droplets after the toilet has been flushed

Simulations showed that water cascading down the side of the ceramic hits the opposite side of the bowl and this creates vortices, similar to a tornado or whirlpool. This sends infectious droplets out of the toilet bowl. Pictured, the computer showing the droplets after the toilet has been flushed 

Can coronavirus be spread by faeces? 

A study published in May 2020 in the Lancet found virus particles were present in faeces of COVID-19 patients  nearly 5 weeks after the patients tested negative.

These particles were still viable and could cause faecal-oral transmission of the coronavirus, the Chinese researchers warned. 

Faecal–oral transmission has previously been seen in people with SARS and MERS.  

Researchers say routine stool sample testing, as well as the existing throat swabs. should be used to make sure a person is clear of the virus. 

Scientists also call for strict precautions to prevent transmission from the virus found in faeces. 

A new study shows the toilet seat should be put down before flushing to ensure infectious particles do not drift around the bathroom or cubicle. 

Turbulence from the cascading water designed to remove faecal waste creates vortices which can carry infection droplets from stools up to 3 ft above the water level.  

Up to 60 per cent of the ejected particles rise high above the seat and they can remain airborne for more than a minute.  

Great attention has been paid to airborne transmission, indirect transmission via a surface and direct human-to-human transmission via large droplets produced when coughing or sneezing.

Many people are now wearing masks and using hand sanitiser or anti-viral wipes to reduce the risk of transmission, but few are aware of the risks posed by faeces.

To understand more about the infection risk to others of going to the toilet, researchers from Yangzhou University ran a series of computer simulations. 

They looked at two common types of toilet flushing mechanism, one with a single water inlet and one with two inlets to create a rotating flow.

Simulations showed that water cascading down the side of the ceramic hits the opposite side of the bowl and this creates vortices, similar to a tornado or whirlpool. 

As the water continues to pour in to flush away the deposited waste, the vortices rise into the air.   

Infected droplets, which could be carrying any virus, including influenza or the coronavirus causing the current pandemic,are carried on this wind.

The turbulence can see then rise up to 3ft (one metre) into the air and, once they escape the bowl, the air currents can carry them across a cubicle or bathroom. 

Droplets are so small in size and mass that they remain airborne for more than 60 seconds.   

‘One can foresee that the velocity will be even higher when a toilet is used frequently, such as in the case of a family toilet during a busy time or a public toilet serving a densely populated area,’ said co-author Ji-Xiang Wang, of Yangzhou University. 

The full findings have been published in the journal Physics of Fluids. 

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