First things first: When you go to the bathroom, wash your hands properly when you’re done. Seriously. This is not a drill.
But what to do with those wet hands? Putting them under a hand dryer could end up spreading bacteria in public restrooms, according to research conducted by University of Leeds scientists and published in the Journal of Hospital Infection.
Researchers coated subjects’ hands with Lactobacillus, a harmless bacteria that you don’t typically come across in a public bathroom. The idea was to mimic hands that hadn’t been washed properly. After drying hands, researchers went in and conducted 120 air-sampling tests. They found that Lactobacillus counts in the air were 4½ times higher near high-powered jet dryers than around warm-air dryers. And bacteria counts were 27 times higher near warm-air dryers than when subjects used paper towels.
“Next time you dry your hands in a public toilet using an electric hand dryer, you may be spreading bacteria without knowing it,” University of Leeds School of Medicine professor and study lead Mark Wilcox said in a statement. “You may also be splattered with bugs from other people’s hands.”
Another set of subjects coated their hands in paint to mimic how bacteria could be spreading.
The European Tissue Symposium, a group of tissue-product makers, funded the research. A spokesperson for Dyson, a company that makes hand dryers, told the Telegraph that the research was flawed. “They have tested glove-covered hands, which have been contaminated with unrealistically high levels of bacteria, and not washed,” she said.
Previous research has looked more closely at the amount of bacteria left on the hands of people using hand dryers versus paper towels, and found that one of the biggest keys to reducing bacteria was getting hands as dry as possible. A 2011 study published in the Journal of Applied Microbiologyfound that paper towels consistently out-performed hand dryers. For that study, subjects handled chicken and then washed their hands, in order to replicate a common scenario.