Public toilets named COVID-19 risk as study finds virus 'clouds'

It's important to close the toilet lid before flushing for sanitation reasons, but doing so isn't possible in many public facilities located in the United States and many other countries. These public toilets not only often lack a lid, but also flush with a greater velocity than most home toilets, paving the way for potential 'clouds' of particles containing viruses like the one behind COVID-19.

Some viruses like the novel coronavirus spread in tiny droplets of moisture that can result from sneezing, coughing, or even just breathing heavily. Masks are used as a way to reduce the spread of these droplets, but breathing isn't the only potential source. A new study from the American Institute of Physics found that flushing toilets without first closing a lid could potentially disperse the virus as clouds of tiny droplets.

Public toilets often come in one of two designs: single inlet and two inlets. A single inlet toilet is a kind that flushes the water directly down the drain, whereas a dual-inlet toilet directs the water in such a way that it creates a rotation, the kind typical of many consumer-grade toilet models.

Using precise computer models and physics, researchers studied the effects of these flushing mechanisms on tiny droplet creation, finding that both single- and dual-inlet toilets result in 'clouds' of particles that can disperse bacteria and viruses into the nearby environment.

In the case of toilets that feature two water inlets, the study found that nearly 60-percent of the resulting ejected tiny droplets are able to rise above the seat to heights up to around 3 feet. These 'clouds' of droplets were found to hang in the air for more than a minute, eventually dropping down onto surfaces. While in the air, these droplets could be inhaled by anyone in the bathroom.

There's an obvious solution to this issue, which is closing the toilet seat before flushing. This is not possible on most public toilets, however, putting anyone who uses them at risk of contracting certain viruses, including the novel coronavirus. Researchers encourage companies to start manufacturing public-use toilets that feature automatically closing lids before the flush takes place.

In the meantime, it may be safest to avoid public restrooms; in cases where this isn't possible, such as while working a long shift, the public should make sure to wear properly fitted face masks, to avoid touching their face, and to wash their hands thoroughly with hot, soapy water as soon as they are finished.