Air hand dryers spread contamination more than paper towels, study finds

A person is seen drying their hands with paper towel. (Pexels)

TORONTO — A new study has found that high-speed air hand dryers can spread bacteria from poorly washed hands to clothing and surfaces beyond the bathroom.

The study, conducted by researchers out of the United Kingdom, found that air dryers not only leave more contamination on hands compared to paper towels, but they can also spread germs onto clothing during drying, transferring more bacteria to other surfaces.

The findings were published Wednesday in Infection Control & Hospital Epidemiology, the peer-reviewed journal of the Society for Healthcare Epidemiology of America (SHEA). The study was funded by the European Tissue Symposium.

The study was conducted in a controlled, health-care facility where volunteers sanitized their hands with 70 per cent alcohol disinfectant, dipped them in a viral solution, shook them off, and then dried them either using an air dryer or paper towels. Participants did this while wearing an apron to test if any contaminants were spread to their clothing.

According to the study, volunteers' palms and fingertips were sampled "immediately" after hand drying to establish a base level of hand contamination before leaving the bathroom.

Researchers reported that the volunteers then walked a pre-determined path through the hospital and touched commonly used surfaces including elevator and ward buttons, as well as telephones and their aprons.

The researchers collected samples from surfaces that the volunteers touched, and also from their clothing. Surfaces were disinfected with chlorine wipes before and after sampling, followed by routine cleaning.

On average, the study found that the levels of contamination on surfaces volunteers touched were 10 times higher after hands were dried with an air dryer than they were with paper towels.

The study reported that even if hands were washed poorly, drying them using paper towels rather than an air dryer significantly reduced the "microbial burden" of further contamination.

The researchers also found evidence of "greater microbial transfer" to the aprons when volunteers used the air dryer. The study reports that this transfer of microbes to the volunteers' clothing after using the hand dryer also contributed to an increased spread of germs.

"A fundamental principle of infection prevention practice is to minimize the potential for microbe dispersal. Thus, our findings question the use of hand drying with jet air dryers in a hospital setting," the study's authors wrote.

However, Ines Moura, one of the study's authors and a research fellow at the University of Leeds, said in a press release that the findings can be applied to other facilities, including public bathrooms.

"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," Moura said.

She added that the new research provides a better understanding of how the choice of a hand drying method can "complement good hand hygiene and help reduce the contamination remaining on the hands following inadequate hand washing."

The volunteers were not given specific instructions on how to wash their hands, and the authors note that future studies should investigate how the method and length of handwashing may impact the degree of bacteria spread and surface contamination.