Public toilets are often not pleasant places to go, but our bathrooms at home are dirtier than you think.
A team of Colorado University engineers ran an experiment during a free week; it wasn’t a waste of time.
Using two lasers, one that shone continuously on and above the toilet and another that sent fast pulses of light over the same area, the team found that airborne particles from flushed toilets are fast. The aerosols reached speeds of 6.6 feet per second and rose 4.9 feet above the toilet within 8 seconds. The smaller particles (less than 5 microns) remained suspended for minutes or longer.
“People have known that toilets emit aerosols, but they haven’t been able to see them,” said John Crimaldi, lead author of the study and professor of civil, environmental, and architectural engineering. “We show that this thing is a much more energetic and rapidly spreading plume than even the people who knew about this understood.”
The energetic, airborne water particles headed mostly upwards and backward towards the rear wall, but their movement was unpredictable. The plume also rose to the lab’s ceiling and, with nowhere else to go, moved outward from the wall and spread forward into the room.
They also measured the airborne particles with an optical particle counter, a device that sucks a sample of air in through a small tube and shines a light on it, allowing it to count and measure the particles. Smaller particles float longer and can escape nose hairs and reach deeper into one’s lungs—making them more hazardous to human health—so knowing how many particles and what size they are was also important.
The experimental setup did not include solid waste or toilet paper in the bowl, and there were no stalls or people moving around. These real-life variables could all exacerbate the problem, said Crimaldi.
Understanding the trajectories and velocities of these particles—which can transport pathogens such as E. coli, C. difficile, noroviruses, and adenoviruses—is vital for mitigating exposure risk through disinfection and ventilation strategies or improved toilet and flush design.
You can watch their videos here: Aerosol visualization with gre [VIDEO] | EurekAlert! Science News Releases
