How do you dry your hands?
Did you know that wet hands can spread up to 1000 times more bacteria than dry hands?1 That is why hand drying is the important final step of a hand hygiene procedure.
The most common hand drying methods involve the use of paper towels, continuous paper rolls and a wide range of electrical hand dryers (warm air, cold air, jet air etc.). The choice of method varies based on practical and economic reasons. Hand drying methods have been studied with the aim of determining which is the most environmental friendly, the most effective in drying hands and the more appropriate to avoid the spread of germs.
Warm air hand dryers have been recognised as being more environmental friendly than the use of roll paper towels 2, however the results relating to their hygiene are less positive. A review of hand washing in the retail food industry 3 suggested that air dryers should not be used, because they accumulate aerosol from toilets and can then contaminate hands with the air blowing through the outlet. This finding was confirmed by another study 4 that found microorganisms such as Staphylococcus heamolyticus, Pseudomonas alcaligenes and Bacillus cereus were emitted from all the hand dryers in washrooms sampled for the investigation. In other cases warm air hand dryers have been recognised "safe" in terms of aerosol liberation 5 and able to reduce the level of airborne microorganisms from 40% to 75% comparing air inlets with air outlets 6.
In a recent study paper towels, warm air dryers and jet air dryers were compared for virus dispersal from artificially contaminated hands during the drying process 7. The authors found that the jet hand dryer lead to a significantly greater and further dispersal of the surrogate virus used for the experiment than the warm hand dryer and the paper towels respectively. These results are in line with other findings where jet dryers were demonstrated to disperse more microbial contamination than other drying methods (paper towels, roller towels, warm air dryer)8, 9. However along with the use of paper towels comes the issue of how and where to appropriately store them before use and how to dispose of them after use. Microorganisms are transferred from people's hands to the paper towels, which can then potentially act as a bacteriological reservoir if paper towel disposal was not managed correctly6.
Based on the limited number of studies of hand drying methods, the answer to the question of whether hand dryers are better or worse than paper towels is unclear. Some of the studies were performed following "extreme" protocols that don't reflect a real world environment. It is acceptable though that many hand dryers are slow and inefficient4, leaving the hands of users moist and more susceptible to transmit and receive contamination.
- Smith JM, Lokhorst DB, 2009. Infection control: can nurses improve hand hygiene practices? J Undergraduate Nurs: Scholarsh. 11(1), 1-6.
- Joseph T, Kelly B, Jahanfar A, Brajesh D. 2015. A comparative life cycle assessment of conventional hand dryer and roll paper towel as hand drying methods. Sci tot environ. 515–516, 109–117.
- Snyder OP. 1998. Hand washing for retail food operations – a review. Dairy Food Environ. Sanitation 18, 149-162. PDF - 27.9 MB
- Alharbi SA, Salem SH, Chinnathambi A, Alharbi NS, ME Zayed, BO Al-Johnny, Wainwright M. 2016. Assessment of the bacterial contamination of hand air dryer in washrooms. Saudi J Biol Sci 23, 268-271.
- Matthews JA and Newsom SWB. 1987. Hot air electric hand driers compared with paper towels for potential spread of airborne bacteria. J Hosp Infect 9, 85-88.
- Taylor JH, Brown KL, Toivenen J and Holah JT. 2000. A microbiological evaluation of warm air hand driers with respect to hand hygiene and the washroom environment. J App Microb 89, 910-919.
- Kimmit PT and Redway KF. 2016. Evaluation of the potential for virus dispersal during hand drying: a comparison of three methods. J Appl Microbiol. 120 (2): 478-486.
- Best EL and Redway K. 2015. Comparison of different hand drying methods: the potential for microbe dispersal and contamination. J Hosp Infect 89, 215–217.
- Margas E, Maguire E, Berland CR, Welander F and Holah JT. 2013. Assessment of the environmental microbiological cross contamination following hand drying with paper hand towels or an air blade dryer. J Appl Microbiol 115, 572–582.