Hand Dryer Air Sample Collection Experiment
Fungi and Bacteria Proliferate After Overnight Cultivation
A British scientist has warned against using hand dryers after washing hands in public restrooms, advising people to use paper towels instead. This is because public restroom hand dryers harbor numerous bacteria.
Recently, the British media outlet Daily Mail introduced a TikTok video by a scientist operating under the name 'Devon Science.' Devon Science compared the bacteria in the air from a public restroom hand dryer with that of regular air using petri dishes. After collecting samples, he cultured them overnight. The next day, the petri dish containing the hand dryer air sample showed stains of various colors such as white, yellow, and black. These were different types of bacteria and fungi. In contrast, the petri dish with the regular air sample was spotless.
In another experiment, Devon Science wiped his hands with paper towels provided in the public restroom and then pressed the towels onto petri dishes. Although some bacteria were found on the paper towels, the amount was significantly less compared to the hand dryer. Additionally, it was confirmed that as the air circulates inside the restroom, bacteria and viruses adhere to both the inside and outside of the hand dryer, and using the hand dryer blows these microorganisms outward.
When Devon Science swabbed the inside of the hand dryer and transferred it to a petri dish, it was filled with bacteria similar to those found in the air emitted by the dryer. The air vent inside the dryer was so dirty that the swab turned black. Devon Science explained, "Bacteria exist inside the hand dryer, so I do not use hand dryers and instead use paper towels or shake my hands dry."
As of the 17th, this experimental video has recorded over 4.7 million views on TikTok.
Devon Science did not specify exactly which bacteria were detected in this experiment. However, previous studies have found bacteria such as E. coli, hepatitis viruses, and bacteria commonly found in feces on public restroom hand dryers.
In 2018, researchers from the University of Connecticut and Quinnipiac University conducted an experiment to determine whether hand dryers in public restrooms suck in bacteria from the air and spray them onto freshly washed hands. The researchers exposed petri dishes to the air from hand dryers for 30 seconds. They confirmed up to 254 bacterial colonies on the petri dishes. Then, they attached a high-efficiency particulate air (HEPA) filter to block bacteria in the air from passing through the hand dryer. As a result, the amount of bacteria on the dishes decreased by 75%. This indicates that most of the bacteria sprayed from hand dryers originated from the air inside the public restroom.
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