Automatic hand dryers in men’s and women’s public restrooms can harbor and spread bacteria, including Staphylococcus and fecal matter, according to research presented during ASM Microbe, which is being held virtually this year.
To assess the contamination of public restroom hand dryers, Craig Oberg, PhD, Brady Distinguished Professor of Microbiology at Weber State University in Ogden, Utah, and two undergraduate students collected samples using 3M Quickswabs from three different locations in each hand dryer — the top of the dryer above the air vents, in the middle beneath the air vents on the internal part of the dryer and the bottom of the dryer.
“Initially, the students were looking for contamination on exercise equipment, then they started looking at other common use equipment in gym areas and restrooms when they settled on hand dryers, especially since they have the potential to aerosolize into the surrounding area,” Oberg told Healio.
Results of the study showed that the bottom of dryers in both the men’s and women’s restrooms had the most contamination, with an average of about 300 organisms/5 cm2, followed by the middle section, which had roughly half as many organisms, averaging 140 organisms/5 cm2 and the top of the dryer, which contained 75 organisms/5 cm2. The researchers said there was no overall difference between the two brands of dryers tested in the study — Dyson Airblade and Mediclinics Dualflow Plus.
As far as finding safer ways to use the dryers, Oberg said the best option is to redesign them with internal ultraviolet light sources to prevent the buildup of microorganisms inside the dryer.
“We recommend that the inside of the dryer be cleaned as part of the bathroom cleaning schedule, which would mean turning off the dryer, then cleaning the hand chamber manually with disinfectant,” he said, adding that using paper towels is likely a safer option, provided that they are not already carrying some microorganisms.
“I think there is certainly the possibility of thinking your hands are clean when they may have been inoculated with micrograms while being dried,” Oberg said. “Our next study is to determine if microorganisms residing on the inside of the dryer readily transmit to the hand. I suspect that would be the case.”