‘The Ick Factor’: Watch Scientists Illuminate Thousands of Micro-Droplets Spewed by Flushing Toilet
In a study by the University of Colorado Boulder, physicists used lasers to illuminate micro-droplets of “toilet plume” thrown up when a toilet is flushed.”
A 2020 study found that more than half of UK residents didn’t close the toilet lid before flushing, allowing “toilet plume” to spread potentially infectious pathogens several feet away from the toilet.Thanks to a group of scientists at the University of Colorado Boulder, we will never see toilets and their contents the same way again.A summary of their research was published in Scientific Reports on Thursday, describing how they managed to visualize the typically-invisible droplets of water that splash out of a toilet when it flushes.“We are using lasers to look at what is ejected out of a commercial toilet when it is flushed,” John Crimaldi, lead author on the study and professor of civil, environmental, and architectural engineering, said in a news release. “The laser light is being shown in a thin sheet and it just reflects off the particles and then our eyes or the camera are able to pick them up and visualize them.”“When the toilet is flushed, it emits these very small, aerosolized particles, and they range from as small as tenths of microns up to potentially as large as almost 1 millimeter. The very large particles fall out quickly, the smaller particles remain suspended,” he explained.“There’s obviously the ‘ick’ factor,” Crimaldi noted, recalling that prior studies have shown that pathogens can persist in a toilet bowl for several dozens of flushes after being deposited there. “From a public health perspective, it’s really important to understand this.”Toilets can harbor any number of bacteria contained in human feces, including e. Coli and m. tuberculosis, as well as viruses passed from the body like influenza, norovirus, and SARS. Some studies have suggested that “toilet plume” could be a disease vector for norovirus on ships and airliners, and that SARS may have spread this way during the 2002-4 outbreak. However, there is no direct experimentational proof of disease transmission via toilet plume.Crimaldi cautioned: “We aren’t epidemiologists, we’re not in public health, we’re engineers and physicists. Our role is to understand the physics of this mechanism and show that that could lead to exposure to pathogens and then to work, ideally, with other people down the road to try to minimize the transmission.”“I think this will change your relationship with toilets,” he added.Past studies have shown that the design of the toilet greatly influences the size and spread of the toilet plume, and generally increases with water pressure in the toilet. The least-pluminous toilets are modern siphoning toilets and the low-flush gravity-flow toilets commonly found in homes. They also found that closing the toilet lid before flushing could cut the spread of plume by a factor of 12.One study performed by bathroom cleaner manufacturer Harpic in 2020 also used high-speed cameras to track the distance toilet plume droplets flew, with some landing up to six feet (1 meter) away. It was released as part of a #CloseTheLid campaign.
