RELATED: Never Use This Stall in a Public Bathroom, Experts Warn. In a small 2020 study, researchers from the University of Leeds in the U.K. conducted an experiment in a hospital setting using four volunteers. First, each had their hands contaminated with a bacteriophage, which is a virus that infects bacteria but is harmless to humans. Then, each volunteer went into a public bathroom in the hospital and skipped scrubbing their hands clean before using an electric air dryer or paper towels to dry off, simulating what would happen in the case of someone not correctly washing.ae0fcc31ae342fd3a1346ebb1f342fcb The volunteers then touched nearly a dozen surfaces around the hospital, including stair railings, door handles, elevators, phones, and even aprons and medical equipment. After taking samples, researchers found that using paper towels and air dryers both reduced the amount of bacteria on hands. However, volunteers who used the air dryer method of drying their hands left “significantly greater environmental contamination” on 10 out of 11 surfaces, averaging ten times the amount compared to those who had used paper towels. The authors wrote that the findings showed a clear advantage to wiping your hands dry after washing to cut down on the spread of germs. But they also noted that it was becoming common for hospitals and healthcare providers throughout the U.K. to swap out paper towels for jet air dryers in public bathrooms. “There are clear differences, according to hand drying method, in the residual microbial contamination of the subject’s hands and body. Crucially, these differences in contamination translate into significantly greater levels of microbe contamination after jet air drying versus paper towel use from hands and body beyond the toilet/washroom,” the authors wrote. “As public toilets are used by patients, visitors, and staff, the hand drying method chosen has the potential to increase (using jet dryers) or reduce (using paper towels) pathogen transmission in hospital settings.” In light of the COVID-19 pandemic, the researchers said that the superior drying method could have a noticeable effect, concluding: “Paper towels should be the preferred way to dry hands after washing and so reduce the risk of virus contamination and spread.”

RELATED: For more up-to-date information, sign up for our daily newsletter. While the small study—which has not been peer-reviewed and was intended as a presentation for a conference that was canceled due to the pandemic—does provide some initial insight, some experts raised questions about the methodology. According to Donald Schaffner, PhD, a professor at Rutgers University and an expert in cross-contamination and handwashing who didn’t work on the study, further research was required to see if wetter hands may have in fact been responsible for the increased transmission of germs. “This study confirms previous research showing that paper towels may assist in the removal of micro-organisms from hands following a handwash, or they may just show that dryer hands spread fewer bacteria,” he told Newsweek. “The research would have been improved if the authors have investigated paper towels to see if the virus was present.” Still, others pointed out that the study demonstrated how important it was to scrub up well overall. “Clearly, how much virus remains on peoples’ hands after washing depends to a large extent on how efficiently people are at washing their own hands,” Paul Hunter, MD, a professor of medicine at the University of East Anglia, said in response to the study. “If people do not wash their hands properly, then other people may be at risk if standing close to someone using such a jet dryer. This study reinforces the need to wash hands properly so as much virus is removed as possible before drying.” But how can you be sure you’re washing up enough? The Centers for Disease Control (CDC) recommends lathering hands with soap and scrubbing them together for at least 20 seconds before rinsing them under running water—or as long as it takes to sing “happy birthday” twice if you’re concerned about counting too quickly. RELATED: The One Thing You Should Never Do After You Flush, New Study Says.