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Several studies have found that air hand dryers can blow bacteria back onto your hands and spread germs more than paper towels. Real People Group/Getty Images
  • A new study indicates that using air hand dryers to dry your hands may spread germs more than paper towels.
  • Previous studies have also found that air hand dryers can blow bacteria from bathroom air back onto your hands.
  • Experts say that proper handwashing is still the most important action we can take to prevent transmitting COVID-19.

During the COVID-19 pandemic, many businesses have turned to touch-free methods to cut down on opportunities for spreading germs.

For example, many restaurants now provide a QR code for viewing their menu on your smartphone in lieu of traditional paper menus.

In addition, many business restrooms use hand dryers rather than paper towels.

However, according to a new study published in Infection Control & Hospital Epidemiology, the latter may not be as effective as we might think it is.

High-speed air dryers may actually leave more contamination on your hands than paper towels do.

In addition, they may spread germs onto your clothes, leading to more of them being transferred to other surfaces.

Dr. Paul S. Pottinger, a board certified physician and director of the Infectious Diseases & Tropical Medicine Clinic at the University of Washington Medical Center-Montlake, who was not involved in the new study, said the purpose of the new research was to attempt to understand whether different hand drying methods might affect the spread of germs in a hospital environment.

“To understand that, [the researchers] simulated contaminated hands by treating hands (either bare or gloved) with a harmless virus, then asked participants to dry their hands, either using paper towels or using an air dryer,” Pottinger said.

They then detected the amount of virus that was transferred to various surfaces around the hospital.

When the researchers compared the two drying methods, they found that the people who dried their hands using the air dryer had spread more of the virus.

Unfortunately, we may not be able to apply the findings from this particular study in our battle against COVID-19.

According to Robert Smith, PhD, assistant professor in the department of biological sciences at Nova Southeastern University Halmos College of Arts and Sciences, there were several problems with the study.

“The amount [of the virus] that they put on is far above what one would reasonably expect to encounter in a normal environment. Thus, the study is likely overestimating how much virus is transferred to surfaces and remains on someone’s hands,” Smith said.

He pointed out that the study didn’t control for handwashing procedure. What that means is that researchers didn’t describe how participants washed their hands, nor did researchers ensure that everyone in the study was following the same procedure.

“Handwashing has been shown to be the single [most] effective way to cut down the transmission and spread of microbes, so this would be important to regulate in the study,” he said.

He added that the study participants knew if they got the harmless virus on their hands or not. This could have biased them to behave differently for each treatment.

“The sample size is really, really small for a study like this. To have a change in the way that we think about handwashing, the study would have to be large and better planned out,” Smith said.

But while the extreme conditions of this particular study may not be entirely applicable to real-world situations, previous studies have found that hot-air dryers can blow large amounts of spores from bathroom air directly onto your hands.

Essentially, air dryers may be bathing your hands in hefty doses of bacteria, including some that are typically found in feces.

As we try to navigate safely though the world during the COVID-19 pandemic, it may be best to avoid air dryers in public restrooms as an extra precaution.

However, it should be noted that studies have not found a direct link between the use of hand air dryers and contracting the coronavirus.

Pottinger said that the important thing is to wash our hands carefully using soap and water for at least 30 seconds.

“The way in which we choose to dry our hands is comparatively less important,” Pottinger said. “But, as the study suggests, there may be benefit in choosing paper towel over electric hand dryer.”

“In either case, the most important thing is to ensure that we prevent our freshly cleaned hands from coming into contact with contaminated surfaces, including a paper towel dispenser or a hand dryer,” he explained.

Pottinger said he personally does choose paper towels, not only for the reasons indicated in the study, but because it allows him to grasp the restroom doorknob with the paper towel covering his hand to avoid contaminating it.

Smith agreed that properly washing your hands is the most important part of the process.

“It doesn’t matter what you dry your hands with if there is bacteria and virus all over them because you didn’t do a good job washing them in the first place,” he said.

Smith added that the second best choice to handwashing is using a hand sanitizer with at least 60 percent alcohol.

He cautioned, however, that this method doesn’t kill microbes as effectively as soap, water, and proper handwashing technique.