Flushing toilets without lids sends fecal particles whizzing through the air, where they are sucked up by dryers, warmed, and then spit out again on your hands
Most of us were taught public restrooms were among the most germ-ridden places on Earth. Public health announcements warn us to wash and dry our hands, to prevent the transmission of disease.
A new study says we should ignore that advice and skip the hand dryer.
“The full cycle goes like this,” reports BoingBoing: “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.”
The paper, published in Applied and Environmental Microbiology, involved the study of three separate bathrooms in the University of Connecticut.
Scientists set off hand dryers in the bathrooms and placed special plates beneath them for 30 seconds. Tests revealed between 18 and 30 colonies of bacteria on each plate.
HEPA filters could reduce bacteria transmission fourfold, the researchers said, but not entirely. In a final test of dryers with HEPA filters, the blowers still stirred up potential pathogens, including Staphylococcus aureus.
“The findings should be a wake-up call to managers of research and clinical settings,” the study’s authors wrote.
They also noted that Clostridium difficile—a devastating diarrheal plague—also forms spores that can easily be launched 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.
Considering paper towels contribute to massive deforestation, air drying or wiping your hands on your clothes may be the most environmentally friendly choice.