"Toilet Lid Up or Down: Does It Really Matter When Flushing?"
A study from the University of Arizona found that closing the toilet lid before flushing does not substantially reduce cross-contamination of bathroom surfaces by airborne bacterial and viral particles. However, adding a disinfectant to the toilet bowl before flushing and using disinfectant dispensers in the tank significantly reduce cross-contamination. The study involved experiments with E. coli and coliphage MS2 in both public and household toilets, and found that rigorous cleaning with a toilet bowl brush and Lysol reduced contamination by 99.99 percent. The researchers recommend the use of disinfectants to reduce restroom cross-contamination associated with toilet flushing, especially in health care facilities and households with active infections.