Study: Bathroom Hand Dryers Suck in Fecal Bacteria and Blow It on Hands

April 22, 2019 Updated: June 24, 2019

A study discovered that hand dryers in public bathrooms blew bacteria 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 hand driers 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 hand 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 hand 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.

Meanwhile, the authors noted that hand 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 hand 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.

Ice Machines?

BBC Watchdog report found that ice served by some fast food chains was contaminated with fecal bacteria.

A Kentucky Fried Chicken (KFC) bucket of fried chicken is seen in this picture illustration taken April 6, 2017. (Carlo Allegri/Reuters)

More than half of the samples from the major chains—including Burger King, KFC, and McDonald’s—were contaminated with the bacteria, according to the BBC documentary. The investigation was made after it had been revealed that ice from coffee chains like Starbucks also contained fecal bacteria.

Out of 10 samples that were obtained from each of the three chains, seven were found to be contaminated from KFC, six were contaminated from Burger King, and three from McDonald’s, the Watchdog report stated. Five of the seven tested at KFC were noted as “severe” in the report.

McDonalds
A McDonalds in central London, on Sept. 4, 2017. (Tolga Akmen/AFP/Getty Images)

“When we’re finding the sorts of numbers we’re finding here, you have to look at the people making the ice, handling the ice, which they then transfer into customers’ drinks,” said Tony Lewis, who is Head of Policy and Education at the Chartered Institute of Environmental Health, according to The Independent.

“And then you also have to look at hygiene failure with potentially the machines themselves: are they being kept clean?”

KFC has since said it completely shut down the ice machines that were named in the report.

Top photo credit: Tomwsulcer / Creative Commons CC0 1.0 Universal Public Domain Dedication.

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