A scientist recently revealed just how unsanitary hand dryers in public restrooms may be, leaving many feeling uneasy. While many consider hand dryers a clean option, a recent experiment suggests otherwise.
The TikTok account Devon Science shared an experiment by Ruth, the scientist behind the page. In her test, Ruth used two agar plates—petri dishes with a nutrient gel that fosters bacterial and fungal growth. She placed one plate under a hand dryer in a public restroom and waved a second plate in the air in a different room to use as a control.
After incubating the plates overnight, Ruth observed a range of bacteria and fungi on the plate exposed to the hand dryer, while the control plate stayed clean. “This is why I do not use hand dryers,” Ruth concluded in her TikTok video, which has now garnered over three million views. The video has sparked a wave of reactions, with one viewer saying, “I stopped using hand dryers after seeing these videos,” while another joked, “New fear unlocked, cheers.” Another viewer commented, “Ha knew it. Never using them again.”
Following requests to test a Dyson hand dryer, which claims to use HEPA filters for cleaner air, Ruth agreed to conduct a future test on it.
In response to the video’s popularity—and some skepticism about its scientific validity—Ruth posted a follow-up. She clarified, “It’s not a proper scientific experiment. I had two spare agar plates and thought, ‘what can I do with these?’” She explained that the idea for the test came up casually in a conversation with a friend weeks earlier.
Describing the test as “very simple,” Ruth expressed interest in future experiments but urged viewers not to take the results too seriously, calling it “just a bit of fun.” Fun or not, the findings might make you think twice before using a hand dryer next time.