Even after hand washing, viruses can remain on a person’s skin. A recent, small scale study concludes that drying the hands with paper towels removes these pathogens more efficiently than jet dryers

Hand washing is a vital tool in the fight against COVID-19. Scientists have demonstrated that a good hand washing regimen can significantly slow the progress of an outbreak.

However, there is more than one way to clean your hands, and scientists are keen to understand which method is best. A group of researchers recently put hand drying under the microscope.

After washing one’s hands, there may still be residual pathogens on the skin. The researchers wanted to understand which method of drying the hands removed these residual viruses most efficiently and prevented people from transferring them to surfaces.

Specifically, they tested the performance of paper towels and jet dryers.

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The researchers were due to present their findings at the European Congress on Clinical Microbiology and Infectious Diseases. However, this year’s event is no longer taking place because of the SARS-CoV-2 pandemic.

Washing and drying
Hand drying is an essential part of hand washing. Microbes survive better in moisture, and so any that remain attached during washing are more likely to spread to surfaces if people do not dry their hands correctly.

Dr. Ines Moura from the University of Leeds, in the United Kingdom, alongside Duncan Ewin and Prof. Mark Wilcox, also from the University of Leeds, U.K., conducted this recent study.

The scientists enlisted just four volunteers who work in a hospital. The participants simulated contamination of their hands using a preparation of bacteriophages — viruses that infect bacteria. Each person then dried their hands using either paper towels or a jet dryer in a public toilet in the hospital.

Later, the researchers collected samples from 11 public and ward areas, including stair handrails, doors, lift buttons, chairs, phones, stethoscopes, and buttons on access intercoms. This would help the team understand whether the participants had spread contamination into the hospital.

Each of the participants wore an apron during the drying process so that the researchers could measure the contamination of clothing and how it might spread to surfaces.

Which method was best?
The authors explain that both methods of hand drying “significantly reduced phage contamination of hands.” However, after using the jet dryer, there was environmental contamination on all 11 surfaces. The authors explain:

“All surfaces sampled following [jet dryer] use showed phage contamination, compared with six surfaces after [paper towel] use.”

In fact, average surface contamination following hand contact was 10 times higher after jet dryer than hand towel use.

Also, contamination after contact with clothing only occurred after the use of a jet dryer. These findings — if larger studies confirm them — are important, as the authors outline:

“As public toilets are used by patients, visitors, and staff, the hand drying method chosen has the potential to increase or reduce pathogen transmission in hospital settings.”

Issues with the study
Of course, because the study only recruited four participants, it cannot make firm conclusions. Also, it made no effort to randomize. Aside from these factors, there are other substantial issues with the study.

Dr. Graham Wheeler, a medical statistician at University College in London in the U.K., explains:

“In this study, all four volunteers were asked not to wash their hands after contamination, to ‘simulate poor hand washing practices.’ But how many people dry their hands without having washed them first?”

Dr. Wheeler continues: “The authors’ conclusions that people should use paper towels after washing their hands can’t be made from this study because that’s not what the investigators tested; they looked at which drying method reduced cross-contamination from unwashed hands.”

With that said, the recent findings broadly agree with an older review from 2012, which investigated how well these hand drying techniques remove bacteria. The authors of the paper looked at 12 studies and concluded:

“[M]ost studies suggest that paper towels can dry hands efficiently, remove bacteria effectively, and cause less contamination of the washroom environment. From a hygiene viewpoint, paper towels are superior to electric air dryers. Paper towels should be recommended in locations where hygiene is paramount, such as hospitals and clinics.”

In a news release, the authors of the most recent hand drying study echo this sentiment:

“We believe that our results are relevant to the control of the novel coronavirus that is spreading at pace worldwide. Paper towels should be the preferred way to dry hands after washing and so reduce the risk of virus contamination and spread.”