Bathroom dryers may leave hands dirtier, study says

Hand dryers may leave your hands significantly more dirty than before, according to a new study.

The study, the results of which were published in this month’s journal Applied and Environmental Microbiology, found that plates exposed to 30 seconds of a bathroom hand dryer gained at least 18 to 60 colonies of bacteria, while plates exposed to bathroom air for two minutes had fewer than one.

The authors concluded that the “results indicate that many kinds of bacteria, including potential pathogens and spores, can be deposited on hands exposed to bathroom hand dryers, and that spores could be dispersed throughout buildings and deposited on hands by hand dryers.”

Still, the study’s authors, who found that the nozzle of the dryers had minimal bacterial levels, said that more evidence was needed to determine if the dryers were bacteria harbors themselves or simply blew large amounts of contaminated air.

It is already known that bathroom air can contain fecal matter and droplets of urine.

“The more air ya move? The more bacteria stick,” Lead study author Peter Setlow told Business Insider. “And there are a lot of bacteria in bathrooms.”

Setlow, who is in his 70s, told the publication that he’s stopped using hand dryers.

The study noted that hand dryers with certain types of filters, called HEPA filters for high efficiency particulate air, could reduce the depositing of the bacteria fourfold.

“Consequently, this study has implications for the control of opportunistic bacterial pathogens and spores in public environments including health care settings,” the authors wrote.