"The Lid Debate: Does Flushing with the Toilet Lid Up or Down Affect Viral Contamination?"
A study from the University of Arizona found that closing the toilet lid before flushing does not substantially reduce airborne contamination from toilet plumes. However, adding a disinfectant to the toilet bowl before flushing and using disinfectant dispensers in the tank can significantly reduce cross-contamination. Research has shown that even smaller droplets from toilet plumes can carry bacteria and viruses, potentially spreading disease. While previous studies suggested that closing the lid could reduce airborne droplets, it was found that doing so increased the diameter of the droplets and bacteria concentration, and airborne microdroplets were still detectable for a longer period with the lid down.