Using the bathroom hand dryer just flings poo particles all over you, study finds

The Bacillus subtilis emitter stares you right in the face as you wash your hands.
The Bacillus subtilis emitter stares you right in the face as you wash your hands. Wikimedia Commons

The next time you’re done washing your hands in a public restroom, maybe make your next stop the paper towel dispenser.

That’s what a group of scientists at the University of Connecticut would advise, anyway.

They found out by asking themselves, “How clean are the restrooms where I work?” So they placed bacteria-collecting plates in 36 restrooms throughout the university’s academic health center.

The results have been published in the latest issue of Applied and Environmental Microbiology.

As it turns out, the hand dryers in public restrooms are blowing more than hot air. Sure, they’re great at saving paper, but they’re also flinging nasty little poo particles all over the place, including onto the hands and faces of those who use them.

The study was conducted using hot air dryers that do not have high-efficiency particulate air filters. According to CNET, hand dryers made by Dyson come equipped with HEPA filters, and could be the exception to the rule of the UConn study’s findings.

One of the bacteria strains flying through the air was identified as none other than Bacillus subtilis, which is found in the gastrointestinal tracts of humans and other mammals.

And just to add another layer of horror to the mix, if you were to get sick from ingesting a few too many of the poo particles, the B. subtilis researchers found on their plates is resistant to the antibiotic kanamycin.

So have fun with that.

The scientists’ plates that were exposed to hand dryer air for 30 seconds averaged 18-60 bacterial colonies per plate. By contrast, plates that were merely exposed to floating bathroom air for two minutes with the hand dryers off collected less than one bacterial colony on average.

The plates that were exposed to bathroom air moved by a small fan for 20 minutes had averages of 15 and 12 colonies per plate in two buildings tested as well.

But the scientists also say that more important poo-spore research is needed. We still don’t know “if hand dryers provide a reservoir of bacteria or simply blow large amounts of bacterially contaminated air.” It’s the classic, “What came first — the poo spore or the air?” question.

Along with that, the only question that remains is, what to do if the restroom you just got done washing your hands in doesn’t have paper towels?

Hold your breath.

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