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Study: Restroom hand dryers suck in, blow out poo onto users

An exhaustive study has revealed that hand dryers in public bathrooms are blowing out fecal matter onto people’s hands.

The report, published in the Applied and Environmental Microbiology Journal, said that scientists put data-gathering plates under hand dryers at 36 bathrooms around the University of Connecticut’s campus.

According to their findings, the plates had 18-60 colonies of bacteria on average. Plates that were simply left in the public restrooms and not placed under the the dryers had fewer than one colony on average.

The dryer nozzles also contained “minimal bacterial levels,” according to the authors’ findings.

“These 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,” the authors stated.

They also said they were uncertain as to what “organisms” were dispersed by dryers or if “hand dryers provide a reservoir of bacteria or simply blow large amounts of bacterially contaminated air, and whether bacterial spores are deposited on surfaces by hand dryers.”

Some dryers didn’t have high-efficiency particulate air, or HEPA, filters. These filters were common in Dyson dryer models.


But researchers said that they found the HEPA filters didn’t eliminate the bacteria completely, although they did help to decrease it.

Dryers spread poo, bacteria into entire buildings

Meanwhile, the authors noted that dryers are “responsible for spreading pathogenic bacteria, including bacterial spores” throughout entire buildings, not just in bathrooms.

The bacteria Bacillus subtilis PS533 was found in every bathroom they tested, according to the abstract.

Are Paper Towers Better?

Peter Setlow, an author of the study, told Newsweek that “bacteria in bathrooms will come from feces, which can be aerosolized a bit when toilets, especially lidless toilets, are flushed.”

Setlow said that the dryers suck up bathroom air and spew it back on to one’s hands.

“Perhaps the filters weren’t working properly, or the large air column below the hand dryers was sucking in bacteria from unfiltered air adjacent to the forced air column,” Setlow added.

Setlow, who works at the University of Connecticut, said he is sticking with using paper towels. The university added paper towels to all 36 bathrooms following the publication of the study.