Watch out if you don’t put the toilet seat down before flushing, because of nasty bacteria which shoot up into the air.
Flushing the toilet sends a plume of tiny water droplets into the air surrounding it.
Among the most common potentially harmful airborne bacteria propelled from the toilet bowls of indoor bathrooms are E. coli and Staphylococcus aureus (S. aureus).
These can be inhaled, raising the risk of getting a nasty stomach bug or respiratory infection.
Researchers measured the two types of bacteria in two bathrooms within an office building in China.
One contained a squat toilet, which is a ‘hole-in-the-floor’ toilet type popular in China, that people squat over before using, while the other bathroom had a bidet toilet.
Showing their commitment to science, the researchers used actual human stools to test for the bacteria created when flushing both toilets.
This was compared to the bacteria in the air after flushing the toilets when they were empty.
Watch out if you don’t put the toilet seat down before flushing, because of nasty bacteria which shoot up into the air. Pictured: File photo
The concentrations of the bacteria in the air were found to be 16 to 27 per cent lower for E. coli after flushing an empty toilet compared to flushing a stool.
The concentration was 25 to 43 per cent lower for S. aureus.
Researchers say the findings for squat toilets would apply to normal seated toilets as well.
However the study found good ventilation could reduce the proportion of these airborne bacteria particles, which scientists call bioaerosols.
Wajid Ali, who led the study from China University of Geosciences, said: ‘Our findings underscore the substantial health risks posed by bioaerosol exposure in public washrooms.
‘Enhancing ventilation systems by optimising exhaust fan efficiency and air exchange rates can effectively reduce bioaerosol concentrations and exposure risks for the public.’
Bacteria lurking within human waste in toilets is ‘agitated’ when they are flushed, according to the researchers, because of the ‘swirling, splashing, and bubbling’ water.
Previous evidence has shown the nasty microbes hang around in the toilet even after dozens of flushes, but that closing the lid prior to flushing will reduce the amount of bacteria in the air.
Among the most common potentially harmful airborne bacteria propelled from the toilet bowls of indoor bathrooms are E. coli and Staphylococcus aureus (S. aureus). Pictured: File photo
The study looked at people’s likely exposure to airborne bacteria in the bathrooms examined, the probability of getting ill, and then how long someone might expect to be ill.
The period of illness which could be caused by toilet bacteria was calculated using Disability-Adjusted Life Years, which are used by health experts to measure the time people spend unable to live normally in full health.
Most of the measurements of bacteria concentrations from the toilets were found to risk people’s health above the acceptable benchmark for DALYs set by the World Health Organisation.
Inhaling the bacteria could produce symptoms like abdominal cramps, nausea, diarrhoea, and vomiting.
However using an exhaust fan reduced the risk from the bacteria 10-fold.
The study, published in the journal Risk Analysis, highlights the importance of ventilation, noting that compared to private bathrooms, public toilets are particularly risky, because they are used more frequently.
Flushing the toilet before using it unfortunately doesn’t work perfectly, as the water remains contaminated after multiple flushes.
The high percentage of airborne bacteria found in the study was attributed to the interaction between liquid and air during toilet flushing, along with the siphon phenomenon created by the high water flow velocity, which predominantly releases tiny bioaerosol particles.
