A pilot study has again shown that drying hands with paper towels instead of jet dryers results in lower concentrations of viral contamination on hands and clothes. The search for the most hygienic method of drying hands has been the subject of many a scientific study for years. 

The study recently appeared in the latest issue of Infection Control and Hospital Epidemiology. It was conducted in a toilet room used by staff, visitors and patients at Leeds General Hospital in the UK. Spread over a 5-week period, virus transmission from the toilet room to surfaces in the public and clinical areas of the hospital was investigated.

Interestingly, the study was funded by the European Tissue Symposium (ETS). It does mention that ETS had no influence on the study design, data collection, analysis, interpretation or manuscript preparations.

Simulating microbial contamination

Using a bacteriophage, a specialised virus that is harmless to humans, microbial contamination was simulated for 2 ways of drying hands: paper towels and jet dryers. Volunteers disinfected their hands after which they immersed them in a liquid containing a bacteriophage. They did this 2 times: for each hand-drying method, they repeated the process. They shook their hands 3 times to remove excess liquid before drying them. The volunteers wore plastic aprons to measure contamination on their bodies and clothes during hand drying.

Contamination level ten times higher after jet dryer

After using a jet dryer, measurements of all surfaces and samples examined showed levels of bacteriophage contamination above the detection limit. After drying hands with paper towels, contamination was found on only 6 out of 11 surfaces.

For example, after drying hands with jet dryers, contamination was detected after simulated use of a hospital telephone for 10 seconds. Compared to paper towels, contamination levels of the torso and clothing were significantly higher after using jet dryers. On average, levels of contamination of surfaces after drying hands with jet dryers were 10 times higher than with paper towels. The findings indicate a higher risk of microbial spread in a hospital after using a jet dryer

Taking samples from touched surfaces

Immediately after drying, the researchers, Ines Moura PhD, Duncan Ewin BSc and Mark Wilcox MD, took samples from the palm and fingertips. They did this to measure reference levels of hand contamination prior to environmental sampling. The volunteers then traversed a pre-designated route from the toilet room. In doing so, they entered publicly accessible areas and clinical wards. Each time they touched surfaces in the environment with their hands or apron, samples were taken.

The volunteers were also given a stethoscope around their neck, whose chest piece and ear buds remained in contact with their apron for about 7 minutes. The volunteers crossed their arms over their chests for 2 minutes and then placed their arms on the armrests of a chair for 3 minutes. Each surface was sampled using a stick with a sponge moistened with a neutralising buffer. Both before and after sampling, the surfaces were disinfected with wipes containing chlorine.

Results are worrying

The findings indicate a higher risk of microbial spread in a hospital after using a jet dryer. This is probably due to the increased risk of splashing on users. Worryingly, objects and surfaces can become a source of infection for transmissible microorganisms through hand contact. Of particular concern is the significantly greater contamination of objects such as phones and stethoscopes in the immediate vicinity of patients and health professionals after using a jet dryer.

Question marks over use of jet dryers in hospital

Minimising the risk of microbial spread is a fundamental principle of infection prevention. The study shows that microbial contamination of the hands or torso of jet dryer users is directly or indirectly transmitted to surfaces through hand, clothing or skin contact.