When the COVID-19 pandemic began, the fear of contagion from a virus that could be lethal or leave serious consequences made us take extreme hygiene measures and, in addition to using masks and hydroalcoholic gels and washing our hands more frequently, we began to pay attention to the places most likely to contain germs like the coronavirus. Taking precautions helps us avoid infection by SARS-CoV-2…, and many others.
And one of the habits that we should incorporate to protect ourselves from pathogens is to lower the toilet seat before pressing the lever or the flush button because when we do it, a cloud similar to an eruption of Vesuvius is released in the form of small droplets and particles of aerosol that reaches more than 1.5 meters above the seat, as verified by engineers from the University of Colorado Boulder. A finding that confirms the worst fears of germ phobes and that they have published in Scientific reports.
This column is made up of tiny droplets of water and whatever else might be in the toilet bowl, and is invisible to the naked eye, but when illuminated with green lasers it resembles an explosion of microscopic confetti someone had thrown at a disgusting party.
Nearly eight seconds after the discharge, the particles still floated more than five feet above the rim of the bowl, and many remained airborne for more than a minute.
The researchers flushed toilets containing only clean water and did not test the particles in the plume for possible infectivity, but their tools confirmed that each flush goes much further down the bowl than previously thought. In fact, a 2021 study already showed that using public toilets and restrooms increased the risk of contracting COVID.
Particles from the toilet reach the height of the nose
John Criminaldi, the lead author of the study is a professor of hydrology who specializes in fluid mechanics, specifically how air and water transport other materials that flow along with them and focused on toilets at the urging of his Boulder colleague. and co-author Karl Lindenan environmental engineer studying the disinfecting properties of ultraviolet (UV) light and working on the development of a UV-based surface disinfectant.
Wondering where we are exposed to viruses and pathogens, Linden thought about restrooms, specifically the commercial tankless and lidless toilets found in public restrooms. In the United States, most public restrooms are equipped with what is known as a flushometer-style valve, which relies on pressure to push water through the bowl, resulting in a high-powered flush that leaves a fine cloud of water vapor in its wake.
Linden turned to Criminaldi, whose lab uses lasers to visualize fluid motion that is otherwise imperceptible to the human eye. The researchers set up a working toilet in the lab on a metal frame that could be aligned with their lasers, and calibrated the water pressure in the pipes to match that of a traditional commercial bathroom.
They knew their laser would make some aerosols visible, but what they saw stunned them: “It’s like a volcano erupting,” Criminaldi said. The team then trained a pulsed laser and a pair of science cameras on the spray to measure the speed of its individual water particles. The researchers say the aerosols in the “surprisingly energetic and chaotic” plume reached a top speed of two meters per second, or just under four miles per hour, and once airborne, took a while to settle.
Nearly eight seconds after the discharge, the particles were still floating more than five feet above the rim of the bowl, well past nose level for most people, and many remained airborne for more than one minute. “After watching these videos, I’m certainly much more inclined to wear a mask in a public bathroom than I might have been before,” Criminaldi said.
The tests were carried out with toilets that only held clean water, but Crimaldi believes that adding toilet paper, feces and other human waste to the mix would make the situation worse. “I have an intuitive feeling that the presence of solids could exacerbate the problem because there are simply additional things that the water can affect and create more opportunities for this energetic mix of fluids,” he concludes.
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