We think we know a successful flush by what we see go down the pipes. But it turns out that whatever's in your toilet bowl actually has a quite complicated afterlife long after you turn the handle. Splashback, or tiny particles thrust into the air, could be a critical pathway for disease transmission in hospitals, according to new, high-speed flushing footage from a group of medical researchers, mathematicians, and engineers.
MIT researcher and faculty member Lydia Bourouiba studies the intersection between fluid dynamics and disease, in this case the transmission of nasty gut bacteria C. difficile. One of the most common places to catch C. diff, which kills an estimated 14,000 Americans a year, is in a hospital. Still, the rate of infection is increasing, and much of the focus on tackling the spread of the bug is dedicated to bleaching hospital surfaces (bedrails, toilet lids, and the like).
Instead, Bourouiba wanted to find out whether invisible particles emitted by flushing played a role in transmission. That's why she and a multidisciplinary team set up a high-speed camera shooting from the side of a hospital toilet at 1,000 to 2,000 frames per second to capture the pathways of the water.
"There is a tradition of neglect of airborne transmission," Bourouiba said. "And so this approach, using high-speed visualizations, allowed to really try to take a look at the fundamental mechanisms of emissions from an infected host or an infected device, like a toilet," she said.
You can see for yourself how that works in the video above.
The footage shows that small particles, or aerosols, could be the invisible, but abundant killer. Those aerosols are important, Bourouiba explains, because they don't settle on surfaces. Instead of being eliminated by bleach, small particles can then circulate in the air, potentially loaded with pathogenic spores.
The videos above were just the first leg of Bourouiba's ongoing research, recently submitted to the American Physical Society's Gallery of Fluid Motion. The full paper has yet to be published in the coming year, and will rely on further studies on the range of disease transmission by hospital toilets in North America. Bourouiba will also continue to study these types of emissions in her lab at MIT. To her knowledge, no one has yet invented a toilet that solves the problem of splashback.