A new study provides further evidence that drying hands with paper towels spreads fewer potentially-harmful germs in healthcare settings than mechanical hand dryers.

A pilot study to investigate whether micro-organisms that remain present on poorly-washed hands can be transferred beyond the washroom environment to clinical and patient areas found that drying hands with paper towels as opposed to jet air dryers resulted in lower rates of virus contamination on hands and clothing. 

The consequences of these different rates of contamination remaining on hands after drying were measured by sampling a series of surfaces to determine the extent of transmission of a virus beyond the washroom.

Beyond the washroom

The study, peer reviewed in the latest issue of Infection Control and Hospital Epidemiology, was performed in a washroom at Leeds General Infirmary which is used by staff, visitors and patients. 

The study was spaced over a five-week period and investigated virus transmission beyond the washroom to surfaces in the hospital’s public and clinical areas.

A bacteriophage – a specialised virus that is harmless to humans – was used to represent microbial contamination following two types of hand drying: one using paper towels, and the other using jet air dryers. 

Volunteers sanitised their hands before immersion in a liquid containing bacteriophage; they did this twice, once with each hand drying method. 

Hands were then shaken three times to remove excess liquid before drying. 

Volunteers also wore plastic aprons in order to be able to measure body/clothing contamination during hand drying.

Surface contamination

All surfaces and samples investigated had bacteriophage contamination above the limit of detection following jet air dryer use. 

Contamination following hand drying with paper towels occurred on only six of 11 surfaces. For instance, simulated use of a hospital phone for 10 seconds resulted in detectable contamination following hand drying with jet air dryers. 

Trunk and clothing contamination was significantly higher following jet dryers use, compared to paper towels. 

On average, the levels of contamination of surfaces following hand drying with jet air dryers were 10-fold higher than with paper towels.

The researchers – Ines Moura, Duncan Ewin, and Mark Wilcox – sampled the palm and fingertips immediately after drying to measure baseline hand contamination levels before environmental sampling. 

Volunteers then walked from the washroom on a pre-set route that included public and clinical areas. 

And samples were collected from environmental surfaces following contact with hands or apron. 

A stethoscope was placed around the neck, leaving the chest piece and earpiece in contact with the apron for some seven minutes. Volunteers also crossed their arms across their chest for two minutes and then rested them on the arms of a chair for three minutes. 

Each surface was then swabbed with a sponge-stick moistened with neutralising buffer, and surfaces were disinfected with chlorine wipes both before and after sampling.

Increased risk

The findings suggest a higher potential for microbial spread through the hospital following jet air dryer use – likely due to the increased risk of splattering on users. 

This is concerning because objects and surfaces can serve as reservoirs for micro-organisms and be acquired via hand contact. 

The significantly-greater contamination of items in close contact with healthcare professionals and patients – such as phones and stethoscopes – following jet air dryer use is particularly concerning. 

And, moving forward, minimising the potential for microbe dispersal is a fundamental principle of infection prevention. 

The authors said: “This study showed that the microbial contamination of the user’s hands or trunk following jet air dryer use was directly, and indirectly, transferred onto surfaces via hand, clothing or skin contact.

“The pilot study findings question the use of jet air dryers in a hospital setting and support the recommendations of German hospitals and the French SF2H that paper towels should be the prescribed method of hand drying in healthcare settings.”

Previous studies have already established that risk of environmental bacterial contamination was lower when paper towels were used as the method of hand drying as there was less droplet and/or microbe dispersion, and consequently lower levels of toilet surface contamination.

The researchers now recommend that future studies should focus on a greater number of volunteers and potentially also include an investigation of the handwashing process prior to hand drying, exploring how the method and length of hand washing may affect the degree of bacteriophage transfer and surface contamination.