Toilet Plume: Aerosolized Particles Released by Flushing

A toilet plume is the dispersal of fine, largely invisible droplets and aerosol particles ejected from the bowl when a toilet is flushed. The turbulent flush flings particles several feet into the air, where the smallest can remain suspended for tens of minutes and settle onto floors, counters, towels, and toothbrushes. Decades of experiments — beginning in the 1950s and popularized by microbiologist Charles Gerba in 1975 — have documented that pathogens such as norovirus and coronaviruses can be carried by these aerosols, raising concerns about fecal-oral transmission of disease in shared bathrooms. The long-standing folk recommendation has been to close the lid before flushing to trap the plume. The evidence for this is weaker than commonly assumed. A January 2024 study published in the American Journal of Infection Control, using a non-pathogenic virus as a tracer, found no statistically significant difference in overall surface contamination between flushing with the lid up versus down. Closing the lid appeared to redirect the plume — increasing contamination on some surfaces while decreasing it on others — rather than containing it, in part because particles escape through the gaps around the lid. The same research concluded that the only meaningful way to reduce viral particles was disinfection: cleaning the toilet, the bowl water, and nearby surfaces with disinfectant, including vigorous brushing of the bowl. This reframes bathroom hygiene advice: while closing the lid remains harmless and may reduce splatter and odor, it should not be relied on as the primary defense against aerosolized pathogens. Adequate ventilation and regular disinfection of high-touch surfaces are more effective controls.