An Australian study has found no evidence that pathogens such as COVID-19 can be transmitted via the air in public washrooms.

The peer-reviewed paper, published in Science of The Total Environment, analysed 38 studies from 13 countries between 2000 and 2020 to determine the risk of viral and bacterial transmission in public toilets. Several possible transmission modes were considered including inhalation and surface contact.

The use of hand dryers and aerosolization from flush systems did pose some risks, according to study lead Professor Sotiris Vardoulakis. But the chances of transmission were deemed to be low provided that good hygiene protocols were maintained.

"We realise people are worried about using public washrooms during the pandemic," said Professor Sotiris Vardoulakis. "But if you minimise your time in the washroom, wash and dry your hands properly and don't use your mobile phone, eat or drink, then the risks should remain low."

Environmental samples from toilets in COVID-19 wards in Singapore, China, England and Italy revealed the presence of the virus when tested. However, Vardoulakis pointed out that contamination was different to transmission.

He said there were several reasons why toilets posed a low level of risk. "People don't spend a long time in washrooms and don't interact with others," he said.

"And importantly, the aerosols you may inhale when you flush the toilet come from your own human waste. The risk of cross-contamination is not very high."

The study makes 25 recommendations to reduce public toilet contamination and transmission risks including switching to automatic flush systems; closing the toilet lid before flushing; installing electric doors and introducing doorless entryways.