Up or down: Does closing toilet lid matter while flushing?

Researchers from the University of Arizona and Reckitt Benckiser — the maker of Lysol — have found that closing the lid on a toilet does not prevent the spread of aerosolised germs, which can spread to floors, walls, and sinks, Daily Mail reported.

Instead, they suggest disinfecting the toilet and using a scrub brush to prevent the spread of viral pathogens.

Earlier studies have shown that a closed lid can mitigate the spread of bacteria from the flush, but the latest research, published in the American Journal of Infection Control, is an attempt to see if the same goes for smaller viral particles.

They tested viral particles in a residential and public toilet in an office building. They introduced a virus uninfectible to humans into the toilet, flushed it, and then used a sponge to swab the surfaces.

Researchers found no significant difference in virus quantity from bathroom surfaces, lid position, or floor examination.

However, minimal viral contamination was observed on the surrounding walls, with the toilet seat being the most contaminated surface. Similar patterns of contamination were also found in public toilets.

Closing the lid before flushing led to elevated contamination levels to the left and in front of the toilet but a minor reduction in contamination to the right of the toilet, according to the researchers.

Toilet bowls subjected to cleaning with both a brush and a disinfectant, specifically hydrochloric acid, exhibited lower contamination compared to those cleaned solely with a brush.

It also reduces contamination on adjacent surfaces like the restroom floor and toilet brush caddy, with a reduction of over 99.99% on the toilet and over 97% on the brush.

Dr Charles P Gerba, lead author and a professor of virology at the University of Arizona, said: "With results showing that closing toilet lids has no meaningful 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."