Study Shows Limited Impact of Toilet Lid on Airborne Contamination
Introduction
Scientists at the University of Arizona have recently conducted a notable investigation on whether closing the toilet lid before flushing reduces cross-contamination of bathroom surfaces by airborne bacterial and viral particles. Their findings, published in the American Journal of Infection Control, reveal that while closing the toilet lid doesn’t substantially decrease contamination, adding a disinfectant to the toilet bowl before flushing and using disinfectant dispensers in the tank can significantly reduce cross-contamination.
Toilet Plumes and the Spread of Disease
When a toilet is flushed, both large and small droplets can form, generating toilet plumes. These plumes can potentially carry bacteria such as E. coli or viruses like norovirus if an infected person has previously used the toilet. Pathogens can persist in the toilet bowl even after repeated flushes, waiting for an opportunity to be launched into the air and spread diseases. This is especially concerning as larger droplets can settle on surfaces before drying, while smaller droplets can be carried further by natural air currents.
Past Studies on Toilet Plumes
As far back as the 1950s, the first experiments examining the presence of contaminated particles in toilet plumes were conducted. The concept that diseases could be transmitted this way gained popularity after a 1975 study. Recently, physicists and engineers at the University of Colorado, Boulder, were able to visualize toilet plumes using advanced techniques involving green lasers and cameras.
This technique revealed that airborne particles ejected during a flush could reach speeds of up to 6.6 feet per second and a height of 4.9 feet above the toilet within 8 seconds. Smaller particles, measuring less than 5 microns, could remain suspended in the air for over a minute. The visualization provided undeniable evidence of toilet plumes and their potential role in transmittable diseases.
The Role of Closing the Toilet Lid
Previous studies have suggested that closing the toilet lid before flushing could significantly reduce the airborne spread of contaminants. However, researchers at the University of Cork found that while flushing with the lid down reduced airborne droplets by 30 to 60 percent, it also increased droplet size and bacteria concentration. More notably, airborne microdroplets were still detectable for 16 minutes when the lid was down, 11 minutes longer than when flushed with the lid up.
