High-speed hand dryers spread viral contamination more than paper towels

Hand drying with high speed air dryers spread viral contamination more often than with paper towel, a pilot study in the hospital setting finds. 

“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 lead author Dr Ines Moura from the University of Leeds, UK. “Microbes remaining after hand drying can transfer to surfaces via contaminated hands and clothing.”

The study compared surface contamination from volunteers who dried their hands with either high speed air dryers or paper towels, after dipping their hands in a harmless viral solution containing bacteriophages. Those who initially used the high-speed air dryers repeated the assay using paper towels, and vice versa. [Infect Control Hosp Epidemiol 2021;doi:10.1017/ice.2021.43]

Contamination levels were 10-fold higher on surfaces touched by volunteers after drying their hands using air dryer compared with paper towel: 4.1 log₁₀ copies/μL vs 2.9 log₁₀ copies/μL, respectively.

For all samples, surface contamination was significantly higher following hand drying with air dryer vs paper towel across all surfaces examined, including door knob, stairs handrail, chair, ward access button, phone, and stethoscope (p<0.05 for all).

“The significantly greater contamination of items that are in close contact with healthcare professionals and patients, such as phones or stethoscopes, following jet air dryer use is particularly concerning,” noted Moura and co-authors.

Furthermore, viral spread to aprons worn by the volunteers (to simulate transfer to clothing) was more likely following hand drying using air dryer than with paper towel (p<0.05). Also, indirect transfer of bacteriophage from contact with apron led to surface contamination (such as stethoscope and the arm of chair) following air dryer use but not paper towel.    

“We found that drying of hands that were still contaminated (as often occurs after poor washing) reduced the microbial burden, with a significantly greater effect seen following paper towel use compared with jet air dryer use,” said Moura and co-authors.

After hand drying, the microbial load on the hands was significantly reduced by 2 log₁₀ copies/μL using jet air dryer and by 3 log₁₀ copies/μL using paper towel, with the extent of reduction was greater with the latter than the former.

“[The] recommended handwashing practices for healthcare workers are often not followed, with an average adherence of 40 percent, as previously reported,” the researchers pointed out. “Thus, it is important to understand how the choice of an appropriate hand drying method can complement good hand hygiene and help reduce the contamination remaining on the hands following inadequate hand washing.”

“Our results support the recommendation of paper towel use in healthcare settings,” they stated. These findings showed that hand drying with air dryer can lead to microbial spread from poorly cleaned hands to clothing and environmental surfaces beyond the restroom.

“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 Moura.