Germ spreaders or good hygiene? The dirty truth about hand dryers

Prioritizing your health and that of those around you, it's standard practice to wash your hands in public restrooms. A thorough lather with soap and water is essential for eliminating viruses and bacteria you might have encountered. However, the step of using a hand dryer afterwards is where the controversy begins...

In 2018, a study from researchers at the University of Connecticut and Quinnipiac University wanted to test their hypothesis: that hand dryers were spitting out bacteria onto clean, unsuspecting hands.

Photo: Pavel Danilyuk/Pexels

After their experiment, researchers found that petri dishes placed under hand dryers for up to 30 seconds grew up to 254 colonies of bacteria, versus one colony of bacteria or none for those that were simply exposed to bathroom air. The experiment took place in restrooms in a university health sciences building.

Every time a lidless toilet is flushed, a fine mist of microbes gets aerosolized, according to a different study. The fecal cloud can disperse over an area as large as 6m2 (65 square feet). Coughing, breathing and other bodily functions can also worsen air quality and release aerosols.

The 2018 study found that hand dryers were not harboring bacteria within them. Instead, they were concentrating all the nasty bathroom air and depositing what was there on whatever was below the hand dryer (namely, hands).

TikTok user Phone Soap wanted to see for himself how germy the hand air dryers he was encountering in his day-to-day life really were. So he recently replicated parts of the trial above and shared videos for his followers.

Image: phonesoap/TikTok

For the control, he took a petri dish into a bathroom and shook it in the air, simulating shaking your hands dry in the bathroom. Three days after sitting in the incubator, there was no visible germ growth.

Image: phonesoap/TikTok

After holding the petri dish under the hand dryer in the same location as the control, the petri dish was full of nasty growth after three days in the incubator. In this experiment, the hand dryer was a standard model of the Xlerator brand.

Image: phonesoap/TikTok

This was the second-worst sample, collected from a hand dryer in a gas station bathroom.

He also tested out a Dyson airblade at a movie theater. There was definitely less growth than the others, but more than a dozen bacterial colonies were growing.

Image: phonesoap/TikTok

The best results were seen using a hand dryer, also by the same Xlerator brand seen in the most “germy” example, but this time at a store. This suggests that the level of bacteria is greatly affected by what’s floating around the bathroom air.

Image: phonesoap/TikTok

The 2018 study found that the vast majority of microbes detected do not cause disease in healthy people. The one exception was Staphylococcus aureus (pictured), a common cause of skin infections, abscesses, respiratory infections such as sinusitis, and food poisoning. Acinetobacter, another germ found, usually only causes infections in hospitalized people.

Photo: CDC/Unsplash

The study, however, found that retrofitting dryers with HEPA filters reduced bacterial deposits from dyers by fourfold, although it didn’t stop all nasty pathogens.

According to John Ross of Harvard Health Publishing, “your chances of picking up a serious pathogen in a restroom are small.” He said its important to dry your hands because wet hands help bacteria survive, and suggests opting for paper towels.

A small UK study found that a group of volunteers who used a hand drier and walked through a predetermined path in a hospital contaminated surfaces ten times more than volunteers who used paper towels.

The germs were not just on the volunteers’ hands. Instead, it found that they spread to the volunteer’s aprons, and from the aprons, it got on surfaces like chairs.

Given the pathogens in hospital settings, as well as the vulnerable patients, the study’s authors say their results “support the recommendation of paper towel use in healthcare settings.”

Another negative point for hand dryers is that they are loud, so loud in fact that they could damage children’s ears. One study published in the Canadian journal Paediatrics & Child Health found the loudest dryer (a Dyson Airblade) operating at 121 decibels. Anything over 100 decibels can potentially damage children’s hearing.

Hand dryer companies tend to disagree, for obvious reasons. World Dryer, a hand dryer company, says some studies rely on artificial test conditions, sometimes skewed and sponsored by the paper towel industry. It argues there is no connection between hygiene and hand dryers.

World Dryer says part of the conspiracy against hand dryers has to do with the paper towel industry being blown away by its value proposition, with hand dryer users saving 90-99% of costs per year versus paper towels, not to mention all the trees.

A main alternative to single-use paper towels or hand dryers is wiping hands dry on clothing. According to the Mayo Clinic, that’s not the best bet because if your clothing is dirty, it could contaminate your hands and lessen the benefits of hand washing. The prestigious US medical center also says, “currently, it’s unclear which method of hand drying is best.”

Whether blasting hands dry also makes the air breathed in more hazardous was also looked at in a high-quality study from 2022. It concluded that hand dryers are actually better for the air than paper cause it blasts the germs into surfaces (like walls, hands and clothes) via droplets instead letting smaller aerosols float around.