Air dryers spread germs to surfaces beyond the restroom

High speed air dryers can spread germs from poorly washed hands to clothing and then onto other surfaces outside of the restroom, according to a study from the Society for Healthcare Epidemiology of America.

“Pathogens can persist for several hours on hands and up to several months on surfaces, and they can be acquired at a high rate through contact with environmental surfaces,” wrote the researchers.

“Residual hand moisture is associated with increased microorganism transfer from hands to surfaces. Thus, the process of hand drying is essential in minimizing the risk of pathogen spread.”

“Previously, we examined the risk of environmental bacterial contamination in hospital toilets associated with different hand-drying methods. We observed less droplet and/or microbe dispersion, and consequently lower level of toilet surfaces contamination, following hand drying with paper towels compared to a jet air dryer.”

“These observations showed the impact of the hand-drying method on the risk of contamination of the washroom and toilet environment. However, whether these differences could also affect the spread of pathogens beyond the toilets remains unknown, especially as in hospitals, these are used by staff, visitors, and patients.”

To investigate, the researchers conducted an experiment designed to test the role of different hand drying methods in spreading germs outside of the restroom.

Study participants sanitized their hands with 70 percent alcohol disinfectant, dipped them in a harmless viral solution, and then dried them using either an air dryer or paper towels. 

During the experiment, the volunteers wore an apron to test contamination of clothing. The participants then took a predetermined path through the hospital while touching commonly used surfaces, such as elevator buttons. 

The researchers collected samples from surfaces that the volunteers touched, as well as from their aprons.

“Based on the user and surface contamination observed following hand drying using high speed air dryers, we question the choice of air dryers in healthcare settings,” said study co-author Dr. Ines Moura of the University of Leeds. “Microbes remaining after hand drying can transfer to surfaces via contaminated hands and clothing.”

The levels of contamination on surfaces that individuals touched with their hands were ten times higher after hands were dried with an air dryer rather than paper towels. In addition, there was greater microbial transfer to the apron when volunteers used the air dryer. 

“The study was performed in a healthcare setting and has important lessons for health institutions that still have high speed air dryers in restrooms, but the results are also relevant for public restrooms with high foot traffic,” said Dr. Moura.

The study is published in the journal Infection Control and Hospital Epidemiology.

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By Chrissy Sexton, Earth.com Staff Writer