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A study recently published by U.K.-based researchers, and to be presented at the 2019 European Congress on Clinical Microbiology and Infectious Diseases,finds using paper towels is more effective than conventional jet air dryers for removing microbes when drying poorly washed hands.
The debate over which hand-drying method is best probably began shortly after the first air dryer was patented ;in the 1920s. But the ongoing COVID-19 pandemic has brought a laser focus on handwashing and hygiene.
"The problem starts because some people do not wash their hands properly," study author Mark Wilcox, a University of Leeds microbiologist, said in a statement. "When people use a jet-air dryer, the microbes get blown off and spread around the toilet room."
Poorly washed hands
The U.K.-based scientists simulated hand contamination in four volunteers using a bacteriophageTrusted Source. This is a virus that infects bacteria and is harmless to humans.
The participant's hands weren't washed after contamination to simulate poorly washed hands. They were then dried using either paper towels or a jet air dryer.
"We often say that handwashing is the key to preventing the spread of illness. But wet hands increase the risk of transmitting bacteria, so drying is an equally important step in prevention," urgent care specialist Dr. Theresa Lash-Ritter told Cleveland Clinic's Health Essentials series.
Each volunteer wore an apron so the degree of body or clothing contamination during hand-drying could be measured. Drying was done in a hospital public toilet. Samples were collected from public areas after the participants exited.
Virus samples were collected from areas that included doors, chairs, phones, and clothing worn by the study participants.
Jet air dryers don't just blow hot air
Although both paper towels and the jet air dryer removed significant amounts of virus contamination from hands, the research team discovered there was much more environmental contamination after jet air dryer use.
The findings indicate there was fivefold more virus dispersed to clothing. Surface contamination was more than 10 times higher after jet air dryer use compared with hand-drying by paper towel.
According to researchers, this means microbes can't only be transferred directly from hands that are still contaminated after hand-drying, but also indirectly from that person's body, which was contaminated by viruses blown by the jet air dryer blast.
"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 study 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."
They also believe these findings are relevant to controlling the SARS-CoV-2 virus that's spreading worldwide, and that "paper towels should be the preferred way to dry hands after washing and so reduce the risk of virus contamination and spread."
Although it can be argued that this study was too small to firmly establish whether paper towels beat using a jet air dryer, this is only the latest study to discover the same thing.
European study finds jet air dryers contaminate surfaces
Scientists in the United Kingdom, France, and Italy teamed up for a study to settle the question of whether hand dryers or paper towels are best at preventing the spread of germs.
For multiple 4-week periods, the scientists tracked how several bacteria known to cause disease in hospitals spread (like antibiotic-susceptible and resistant Staphylococcus aureusTrusted Source) in multiple public bathrooms of several hospitals.
Each of the bathrooms in the study had both paper towels and a jet air dryer installed. However, only one hand-drying method was allowed per bathroom. This allowed them to compare how each method performed within the same hospital.
Although there were differences between the hospitals, a consistent pattern did emerge. The bathrooms using jet air dryers were covered with more germs than those where only paper towel was used.
"In effect, the dryer creates an aerosol that contaminates the toilet room, including the dryer itself and potentially the sinks, floor and other surfaces, depending on the dryer design and where it is sited," said Wilcox, who supervised this study, in a statement.
An older study found no significant difference
Another study from 2000 concluded differently. That study collected data from 100 volunteers using four different methods of hand-drying:
- cloth towels accessed by a rotary dispenser
- paper towels from a stack on the handwashing sink
- warm forced air from a mechanical hand-activated dryer
- spontaneous room air evaporation
Those researchers concluded there was no significant difference between hand-drying methods. However, they were only measuring the presence of certain bacteria and not viruses like SARS-CoV-2Trusted Source, which is likely to be carried farther.
How to properly wash hands
According to Dr. Nikhil Bhayani, FIDSA, an infectious disease physician with Texas Health Resources, following these five steps will help you clean germs (like the virus that causes COVID-19) from your hands — which means it won't matter which hand-drying method you use:
- Wet your hands with clean, running water (warm or cold). Turn off the tap and apply soap.
- Lather your hands by rubbing them together with the soap. Lather the backs of your hands, between your fingers, and under your nails.
- Scrub your hands for at least 20 seconds. "Need a timer?" Bhayani asked. "Hum the 'Happy Birthday' song from beginning to end twice."
- Rinse your hands well under clean, running water.
- Dry your hands using a clean towel, or air-dry them.
The bottom line
Due to the COVID-19 pandemic, routinely washing hands is an essential practice to prevent infection.
However, poor handwashing can leave hands still contaminated with viruses. Recent research finds that using jet air dryers to dry poorly washed hands can spread viruses all over clothing and surfaces.
Experts say that if you wash your hands following the appropriate protocol, the method of drying your hands won't matter: You'll have scrubbed off the bacteria and viruses that could have been spread by the air dryer blast.