The new study has an innocuous name: "Deposition of Bacteria and Bacterial Spores by Bathroom Hot-Air Hand Dryers."
It's findings are anything but (butt?).
The study, published by the American Society for Microbiology, did microbial surveys of bathrooms at the University of Connecticut to find out whether hot-air hand dryers draw in microbes and then blow them back out. The findings were gross — really gross.
"The full cycle goes like this: when you flush a toilet that doesn't have a lid, the turbulence of the flush sends fecal particles into the air, where they hover in a miasmic cloud; when the dryers switch on, they pull these particles in through their intake, heat them up, and spray them onto your moist hands and other moist, hospitable surfaces where their bacteria can thrive," BoingBoing reported.
Said the study:
S533 “was almost certainly dispersed throughout bathrooms in the research areas as spores, which would easily survive desiccation in room air, as well as the elevated temperatures in hand dryer air; however, growing or stationary-phase bacteria would not be nearly so hardy as spores,” the authors note. “However, the facile dispersion of one bacterial strain throughout a research facility should probably be a concern to risk assessors and risk managers when dispersion of potentially pathogenic bacteria is considered.”
In a final test, the researchers did a cursory look at some of the other bacteria the dryers were blowing around. They found that with or without a HEPA filter, the blowers stirred up potential pathogens, including Staphylococcus aureus.
The findings should be a wake-up call to managers of research and clinical settings. The authors note that Clostridium difficile—a devastating and intractable diarrheal plague—also forms spores, and researchers have found that a flushing toilet can easily launch it into the air.
“This suggests another means of C. difficile transmission and one that may not be interrupted by either hand washing or traditional surface decontamination methods,” the authors conclude. “The role of this potential mode of C. difficile transmission is worthy of future study.”
This isn't the first study to find that public bathrooms are filled with disgusting things.
Ian Eames, Professor of Fluid Mechanics at the University College London, told CleanLink: “Fecal matter and droplets of urine can be found in washroom air. These small particles can stay in the air and can be transported around the washroom area. Most hand dryers draw in contaminated air and direct it straight onto your hands. If a hand dryer with a HEPA filter is used, cleaner air is directed onto hands and expelled into the room. Both of these effects are beneficial to washroom users, especially in hospital environments.”