How Toilet Flushing Spreads Bacteria and Illness

Bioaerosol concentrations of two bacteria — Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), exceed the optimal levels set by Centers for Disease Control and Prevention (CDC) after toilet flushing (1^✔ ✔Trusted Source
Experimental study on droplet and bioaerosol emissions from flushing a squat toilet

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How Toilet Flushing Spreads Bacteria

A new study published in Risk Analysis found that inhaling these biological particles can cause abdominal cramps, nausea, diarrhea, and vomiting. The researchers tested squat and bidet toilets in an office building in China.

The emission of bioaerosols with the two bacteria was measured under different flushing and ventilation conditions in both restrooms. They found that squat toilets released 42-62% more S. aureus bacteria and 16-27% more E. coli bacteria than bidet toilets.

In addition, bioaerosol concentrations were 25 to 43 percent (S. aureus) and 16 to 27 percent (E. coli) lower after the first flush of an empty toilet compared to those observed after a second flush (when feces were present). Importantly, the researchers found that active ventilation with an exhaust fan reduced the risk by 10 times.

Better Ventilation Can Reduce Germs in Public Restrooms

“Our findings underscore the substantial health risks posed by bioaerosol exposure in public washrooms,” says lead author Wajid Ali, a PhD student in environmental studies at China University of Geosciences. “Enhancing ventilation systems by optimizing exhaust fan efficiency and air exchange rates can effectively reduce bioaerosol concentrations and exposure risks for the public.”

He adds that the findings for squat toilets apply to seated toilets as well. For public health policymakers, the results of the study provide evidence-based recommendations to define safe bioaerosol exposure limits and promote hygiene practices in public washrooms, ensuring healthier and safer indoor environments.

Reference:

1. Experimental study on droplet and bioaerosol emissions from flushing a squat toilet - (https://www.sciencedirect.com/science/article/abs/pii/S0360132324000040)

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Source-Eurekalert