Flushing toilets can spray airborne pathogens, and closing the lid may not fully stop them

Scientists from Flinders University examined 22 prior investigations and concluded that toilet flushing creates turbulent airflow that lifts microbes from the bowl into the breathing zone, where they can remain suspended for at least 20 seconds. The aerosolised particles, termed bioaerosols, may carry disease agents such as legionella, influenza and norovirus, and larger flush volumes produce more of them. Although the researchers could not definitively assess the impact of bathroom ventilation or whether the lid is up or down, lead author Lira Adiyani recommends closing the lid as a precautionary step.

Co-author Harriet Whiley notes the risk is mainly for immunocompromised people and stresses the need for better design in hospitals and aged-care facilities. The team warns that indoor aerosols are an understudied pathway for infection, with implications for building design and public-health strategies. External expert Lotti Tajouri adds that surfaces in toilets are heavily contaminated, so minimizing contact after flushing is also important.