A scientist has revealed the disgusting reason you should never use a hand dryer in a public toilet and always opt for a paper towel.
An experiment by a scientist called Devon Science on TikTok shows just how much bacteria lurks in the machines, which are sprayed over freshly washed hands.
The video, which has been viewed 4.7 million times, shows the scientist placing a petri dish under a dryer and collecting the bacteria that squirt out.
To make it a fair test, she also collected bacteria from the atmosphere in her laboratory and left both samples overnight.
The next day, the petri dish containing the hand dryer germs showed a variety of different bacteria and fungi speckled across the plate – appearing in white, yellow and black spots.
However, the dish that was waved through the air – to mimic someone shaking their hands dry – remained completely clear.
She admitted that this is why she avoids using hand dryers, opting instead to use paper towels or shaking her hands dry.
An experiment by a scientist called Devon Science on TikTok shows just how much bacteria lurks in the machines, which are sprayed over freshly washed hands. In a video that has been viewed 4.7 million times on the social media site, the scientist is seen turning on the dryer over a petri dish to find out what bacteria would grow.
For the next part of the experiment, Devon Science dabbed toilet paper – which she previously used to dry her hands – onto a petri dish.
Although this also grew a variety of bacteria, it was much less than that from the hand dryer.
Finally, she wiped the vent on the inside of the dryer, which was so dirty that the cotton swab came out black.
The results again showed a petri dish full of different types of bacteria, similar to the insects that come out of the fan.
Following the stomach-churning results, Devon Science said: ‘Now I know where the bacteria come from, they actually live inside the machine.’
Although the lab scientist did not reveal which specific bacteria were captured, previous research suggests that E. coli, hepatitis and bacteria found in feces lurk in public restrooms.
Previous studies have also suggested that hand dryers can fire bacteria onto people’s hands as they draw in the air around them – where the microorganisms can remain.
The scientist compared the bacteria directly from the hand dryer, from the air in the toilet and from the inlet opening of the dryer. She discovered that the drying plates contained the most bacteria
One 2018 studyby researchers from the University of Connecticut and Quinnipiac University, tested whether hot-air hand dryers in public restrooms sucked bacteria from the air and dumped them on freshly washed hands.
The researchers exposed a petri dish to hot air from a hand dryer in the bathroom for 30 seconds.
They identified up to 254 bacterial colonies that germinated in the jar.
They then attached high-efficiency particulate air (HEPA) filters to the hand dryers to prevent bacteria from the air from flowing through the dryer.
When they repeated the test, they found that the amount of bacteria in the dishes had dropped by 75 percent.
This suggested that most of the bacteria sprayed from the hand dryers came from the air in the public toilet.