Is it important to flush the toilet with the lid up or down? A study reveals that it has minor impact

Enlarge / Whether the toilet lid is up or down doesn’t make much difference in the spread of airborne bacterial and viral particles.

This study delves into whether closing the toilet lid before flushing reduces cross-contamination of bathroom surfaces by airborne bacterial and viral particles via “toilet plumes.” While the findings suggest that putting a lid on it doesn’t result in significant reduction in contamination, the use of disinfectant in the toilet bowl before flushing and disinfectant dispensers in the tank have been shown to significantly reduce cross-contamination.
Toilets produce more than just large water droplets when flushed, with even smaller droplets potentially carrying bacteria or viruses, if an infected person has used the toilet. Pathogens can persist in the bowl even after repeated flushes. Larger droplets can settle on surfaces before drying, while smaller ones can travel further on natural air currents.
The notion of disease being spread through toilet plumes was first examined in the 1950s and gained popularity following a 1975 study. In recent times, physicists and engineers at the University of Colorado, Boulder used green lasers and cameras to visualize toilet plumes of tiny airborne particles ejected from toilets during a flush. This research provided vivid video footage demonstrating the movement of the airborne particles.
The study showed that ejected airborne particles could travel at high speeds and reach significant heights. Smaller particles could linger in the air for over a minute. Previous research has suggested that closing the lid before flushing could considerably reduce the airborne spread of contaminants. For instance, a 2019 study observed a reduction in airborne droplets when the toilet lid was down, but this also increased the diameter of the droplets and bacteria concentration. Additionally, microdroplets were detectable in the air 16 minutes after flushing with the lid down, 11 minutes longer than if flushed with the lid up.

Author: OpenAI