It’s long been suspected that hand dryers, especially those quick-drying ones that blast hot air known as jet dryers, are actually way worse at keeping our hands and bathrooms free of disease-causing germs. Worryingly, they could even be spreading illness in hospital bathrooms, new research suggests.
Researchers in the UK, France, and Italy teamed up for the study, hoping to definitively settle the question of how dirty hand dryers can be. For three four-week periods, they tracked the spread of several bacteria known to cause disease in hospitals—such as antibiotic-susceptible and resistant Staphylococcus aureus—in the public bathrooms of three hospitals, one in each country. The six bathrooms included in the study each had a jet dryer installed and could carry paper towels, but only one hand-drying method was used per bathroom. That allowed the team to directly compare how each method performed within the same hospital.
There were some differences between the hospitals—UK bathrooms, for instance, were visited far more often, while Italian bathrooms were much less germy—but a consistent pattern emerged: Bathrooms that used jet dryers were more covered with germs than were bathrooms with only paper towels.
The findings were published in the Journal of Hospital Infection.
In the UK hospital, for example, they found resistant S. aureus three times as frequently in the jet-dryer bathrooms. Similarly, in France, bacteria resistant to multiple broad-spectrum antibiotics were found twice as often in the surrounding dust of jet-dryer bathrooms. These findings are particularly troublesome because resistant superbugs are often created and spread in hospitals, where they can easily infect already sick patients.
The added contamination isn’t entirely the jet dryers’ fault, since people who don’t wash their hands correctly are more likely to have these germs on their hands when they place them in or under the dryer. But the very design of these machines makes for easier germ-spreading.
“In effect, the dryer creates an aerosol that contaminates the toilet room, including the dryer itself and potentially the sinks, floor and other surfaces, depending on the dryer design and where it is sited,” senior author Mark Wilcox, professor of medical microbiology at the University of Leeds in the UK, said in a statement. Paper towels, on the other hand, are thought to absorb the water and bacteria on our hands, more effectively stopping the chain of contamination.
The study isn’t the first, even by these researchers, to find that jet dryers are more capable of spreading germs compared to paper towels and less-powerful warm air dryers. But there is still some debate as to whether this difference actually exists or is meaningful. The companies who produce and sell these dryers, such as Dyson, have criticized the design of these negative studies while touting their own research showing that jet dryers are actually safer. Some independent research has also suggested hand dryers aren’t actually more dangerous.
But given the real-world setting and large scale of the study, the authors argue that the energy-saving benefits of hand dryers aren’t worth the health risks, at least in hospitals. In France, hand dryers are already barred in restrooms where patients stay, though only because of the loud noise they make. Countries and hospitals, the authors said, should tighten their infection control guidelines to ensure that air dryers aren’t used in hospitals at all.