Wait, Are Hand Dryers Good or Bad? I Can’t Keep Track

When it comes to the science of hand washing, the wisdom is pretty well established. But what about after you've scrubbed up? Unlike our understanding of hand washing techniques, the science of hand drying is far from concrete.

It's not that scientists haven't looked at this. Though it's definitely not as popular a research subject as washing, over the years there have been dozens of studies comparing paper towels, air dryers, and roll-cloth towel cabinets. But the results have been all over the map, from finding no significant difference, to finding paper towels to be superior, or hand dryers more hygienic.

And the plot thickens: Most of these studies were funded by either the paper towel industry, or hand dryer companies like Dyson. That doesn't mean these findings weren't accurate, but it makes them harder to parse. So what's the truth?

"I think some of the confusion regarding different research work comes from the fact that different studies ask different questions," explained Patrick Kimmitt, a biomedical researcher at the University of Westminster who had a study on hand dryers published this year.

"Some look at what is on the hands after drying while ours looked at what is in the environment around the dryer after this process."

Unlike a lot of the studies out there, Kimmitt's research was funded only by his university and not any third parties (though, as the researchers disclose in the paper, his co-author has previously received money for work he's done with the European Tissue Symposium). Kimmitt and his team had participants dip gloved hands into a liquid doused with bacteriophage MS2: a type of non-pathogenic virus that behaves the same way a lot of pathogenic viruses (like the flu) do, and is often used in experiments. The participants then dried their hands using either paper towels, a hot air hand dryer, or a jet-air dryer (the really intense dryers like what Dyson makes). The researchers found that the jet-air dryers scattered as many as 1,300 times more virus particles than the paper towel.

Though the study was published in the Journal of Applied Microbiology in February, it recently picked up steam in the media, leading to a lot of sensational headlines such as "Using a Dyson hand dryer is like setting off a viral bomb in a bathroom" and "Dyson hand dryers might be blasting germs and disease everywhere." Dyson fought back, noting that its hand-dryers have been shown to result in fewer germs in previous, Dyson-funded studies, and that its dryers are certified hygienic by the National Sanitation Foundation.

So are jet dryers really a germ-blasting machine or is it all a conspiracy funded by Big Paper Towel?

There are a number of things that need to be considered when looking at a study like this, especially since the history of research is so scattered. First of all, while the jet-air dryers spread higher levels of virus particles than the other two methods, even some of the highest levels (found right next to the dryer or in the air immediately after use) were still less than what can be blasted into the air when you flush a toilet. Second of all, this test was specifically to show what can be scattered around when someone either doesn't wash his or her hands, or doesn't do so properly. Proper hand washing techniques would eliminate a lot of the problem, Kimmitt told me.

"Good hand washing would help a lot here but it doesn't usually take place (to do it right you really need to be trained)," Kimmitt said in an email. "Many people wash with just water, which may be worse than not washing at all, and most do an inadequate job of it when using soap."

It's true: Studies have shown even people who think or say they wash their hands every time they use the restroom actually do it only half to three-quarters of the time. And when they do, they often aren't washing thoroughly enough to eliminate dangerous virus and bacteria. It takes at least 20 seconds of scrubbing to slough off germs—that's as long as the first four lines of a Justin Beiber song.

The researchers told me their study's results could help inform the way high-risk environments, like hospitals, choose to set up hand-washing stations. But in regular public bathrooms, we don't have much say in which hand dryer technology is available. Short of hiring a hand washing referee for every public bathroom (in my dreams), what can we do? Considering studies have shown different benefits for each drying technique, our best bet is to just make sure we're scrubbing up well ourselves, even if our neighbors in the next stall aren't.