Researchers find that closing the toilet lid before flushing does not reduce the spread of viral particles
Impacts of lid closing during toilet flushing and toilet bowl cleaning on viral contamination of surfaces in bathrooms in the United States
Highlights
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Background
Viral aerosols generated during toilet flushing represent a possible route of pathogen transmission. The objective of this study was to determine the impact of closing the toilet lid before flushing on the generation of viral aerosols and cross-contamination of toilet mines.
Methods
A surrogate for viruses in human organisms (bactericophage MS2) was added to household and public toilet bowls and rinsed. The resulting viral contamination of the toilet and other bathroom surfaces was then determined.
Results
After rinsing the 2 inoculated toilets, the toilet seat bottoms averaged 10 7 PFU/100 cm 2. Viral contamination of toilet surfaces did not depend on the position of the toilet lid (up or down).
After cleaning toilet bowls using a bowl brush with or without a commercial product (hydrochloric acid) a 4 log 99.99% reduction in toilet sketch water contamination was observed versus no product. Bowl brush contamination was reduced by 1.6 log 10 (97.64%) when the product was used versus no product.
Figure: Schematic diagram of the bathroom sampling sites for the toilet flush aerosol and lid closing experiment.
Conclusions
These results demonstrate that closing the toilet lid before flushing does not mitigate the risk of contaminating bathroom surfaces and that disinfection of all bathroom surfaces (i.e., toilet edges, floors) may be necessary after flushing. or after brushing the toilet to reduce virus contamination.
Comments
A new study published in the American Journal of Infection Control (AJIC) shows that viral particles spread to many bathroom surfaces during toilet flushing, regardless of whether the toilet lid is facing up or down. In this analysis, the only significant way to reduce viral particles was by disinfecting the toilet, toilet water, and nearby surfaces.
Scientists have long known that the toilet flushing process can aerosolize pathogens expelled into the toilet bowl by a sick person. The aerosol plume created by the force of the discharge can travel five feet or more, spreading pathogens to floors, walls, sinks and other nearby surfaces in a bathroom. Previous studies have found that closing the toilet lid can help reduce the spread of bacterial pathogens, but until now there has been no report on whether the same is true for viral pathogens , which tend to be much smaller than their bacterial counterparts.
In this new study, scientists from the University of Arizona and research firm Reckitt Benckiser analyzed the spread of viral particles induced by toilet flushing, with the lids open and closed to determine any differences in outcome. Using a virus that is not pathogenic to humans as a surrogate for more dangerous viruses, they seeded toilets with different doses of the virus, flushed them, and then collected samples of the water from the toilet bowl as well as the toilet surfaces, the floor and walls.
In a separate analysis of the effectiveness of cleaning the toilet with a disinfectant , samples were also collected from the toilet brush and its caddy. The study included public and domestic toilets; The impact of closing the toilet lid could only be studied with the domestic toilet, as public toilets typically do not have a lid.
With the household toilet, the researchers found that there was no statistical difference in the amount of virus collected from the surfaces of the toilet or the nearby floor whether the toilet was flushed with the lid up or down. Viral contamination of the surrounding walls was minimal in both cases, while the toilet seat was the most contaminated surface. Similar contamination patterns were observed in public toilets.
The study also reviewed the effects of bathroom cleaning, both with and without disinfectant. Cleaning with the brush alone left substantial contamination, but cleaning the toilet bowl with a disinfectant and a brush significantly reduced the amount of viruses found in the toilet. The results show that adding disinfectant to the toilet bowl before flushing or using disinfectant dispensers in the toilet tank were effective ways to reduce contamination caused by flushing.
"In healthcare settings, any potential means of pathogen transmission must be addressed to keep all of our patients, including the most vulnerable, such as immunocompromised individuals, as healthy as possible," said Charles P. Gerba, PhD, professor of virology at the University of Arizona and lead author of this study. "As the results show that closing toilet lids has no significant impact on preventing the spread of viral particles, our study highlights the importance of regular disinfection of toilets to reduce contamination and prevent the spread of viruses." .
Additional findings from the study include:
- Cleaning with disinfectant and brush reduced viral contamination in the toilet by more than 99.99% and on the brush by 97.64%.
- Closing the toilet lid may alter the direction of the aerosol column. In this study, the floor surfaces in front of and to the left of the toilet were more contaminated after flushing with the lid closed than with the lid open, and the floor surfaces to the right of the toilet were less contaminated.
- These findings extend to homes. When a member of a family is sick, particularly with an infection that causes gastroenteritis, regularly incorporating a disinfectant during cleaning or before flushing the toilet can help reduce the spread of the infection to other people in the home.
"This study helps establish a clearer understanding of how pathogens spread and the steps we can take to break those chains of transmission," said Tania Bubb, PhD, RN, CIC, FAPIC, president of APIC 2024. "It also underscores the importance of regular disinfection of surfaces in healthcare settings to reduce the spread of viral infections."
Reference: Crimaldi JP, True AC, Linden KG, Hernandez MT, Larsen LT, Pauls AK. Commercial toilets emit energetic and rapidly spreading aerosol plumes. Sci Rep 2022;12:20493. https://doi.org/10.1038/s41598-022-24686-5.
