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Surprising Science

Study: bathroom hand-dryers just spray germs everywhere

Which is better? Paper towels or electronic hand dryers? Click through to find out. Plus, we give you the best handwashing tips so that you’ll get the cleanest hands.
Big Think

Rarely does a Big Think article start with ‘in bathroom news…’ but here goes: in bathroom news, a study has confirmed what most of us have suspected. Those electronic hand dryers in public bathrooms basically just recirculate extremely dirty air. 

They actually do worse than that: they filter dirty air in the machine, and once that filter gets full enough—which, considering many are in windowless bathrooms, is pretty quickly—it just sprays dirty poo-air all over your hands. Not to gross you out, but the mist of poo-air that hangs above the toilet can be spread about 6m—or 20ft—from the toilet every time it’s flushed. Overwhelmingly, you have little chance of getting sick directly from this *cough* poo-mist directly, but things like the common cold and even staphylococcus (the virus behind food poisoning) hang out in bathrooms for a lot longer than you’d think. So washing your hands is tantamount to not getting sick. 

The University of Connecticut conducted the study, which was recently published in the Journal of Applied and Environmental Microbiology. They held contact plates up to bathroom hand dryers on campus for 30 seconds and tested the plates afterward. They found, depressingly, that the plates had gained between 16 to 60 “colonies” of bacteria after being underneath the dryers. Again, none of these were life-threatening. But dirty poo-air is dirty poo-air and the less of it you have on you, the better. 

Alternatives to these hand-dryers? Well, there’s been a study on that. Wiping your hands on your clothes is most definitely a safer option than using paper towels (which have been chilling in the bathroom for however long) or the now-dreaded electronic hand dryer. 

How to get the cleanest hands: 

  • Put the lid on the toilet before you flush. Flushing aerosolizes your, uh, deposits, and doing so without a lid flings up that aerosolization into the air around the toilet up to 20ft. 
  • Wash your hands for 20-30 seconds under hot water with strong soap. 
  • Wash like a doctor, from your wrists to your fingers. 
  • When done, put your fingers up towards the ceiling. There’s a reason doctors do this on TV: because doctors in real life know that dripping water carries the most germs and can accumulate on your fingertips if you just let your hands hang. 
  • Paper towels might actually be the best bet. They get your hands dryer quicker, which gives them less chance to pick up germs (as germs love wet). However, if you’re not using the right soap, you’re basically rubbing the germs all around your hands. 
  • Gonna use the electronic hand dryer after all? Resist the urge to rub your hands together while using it. You’re multiplying your germ count 15x by doing so. 

And, if you’re guessing that this is the first time that Big Think has used the phrase “dirty poo air” in an article, you’re right. 


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