Should hand air-dryers be used in a healthcare setting?
Research has shown that in a healthcare environment, drying hands with paper towels may provide a superior infection control result than warm air- or jet air-dryers. Cathryn Murphy* examines the research and the extent to which the different methods contribute to air and surface contamination.
Hand hygiene is well recognised as the most effective method of preventing cross-contamination and spread of infectious disease in healthcare environments.1-5 However, we are only now appreciating hand drying as a critical part of the hand hygiene process.6,7
The World Health Organization (WHO) recommends hands washed with soap and water be dried so as to not recontaminate hands.8,9 WHO prefers a single-use towel for hand drying, arguing air-dryers may take too long to dry wet hands and more research is needed regarding aerosolisation of waterborne pathogens associated with their use.9
Hand-drying techniques include spontaneous room air evaporation, cloth towels accessed by a rotary dispenser, stacked paper towels, warm forced air from a mechanical hand-activated dryer that causes evaporation and more recently, jet air-dryers which remove water by shearing forces and dispersal into the air.6,7,10-12
Air-dryers in hospitals
Early researchers considered warm air-dryers (WADs) for use in hospitals13 although the short 30-second WAD drying time was inadequate and longer drying presumed to predispose hands to recontamination.13
Subsequent research funded by WAD manufacturers compared paper towel and WAD use in experimental settings using volunteers. Unsurprisingly, the research concluded that certain WADs were hygienic and appropriate for use in health care and the food industry.14
More contemporary perspectives11,7,10 compared paper towel use to using a WAD with and without ultraviolet light, while hands were rubbed and or held stationary. They concluded that WAD hand drying with or without ultraviolet light was more effective at removing bacteria than paper towel use, but only if hands were held stationary.
The emergence of JADs
To address concerns about increased bacteria associated with vigorous hand rubbing during WAD use and emerging criticism of WADs’ increasing surface and airborne contamination, manufacturers then developed jet air-dryers (JADs).
Unlike WADs that warmed and vertically blew out unfiltered air, JADs were designed to expel high-efficiency particulate air in the form of two high-pressure knives of air at ambient temperature to strip water from hands held apart and drawn upwards through the air stream.
Paper towels prove superior
A 2012 systematic review found paper towels to be superior and more hygienic than air-dryers. It cited noise, surface and airborne contamination as well as associated hand dryness among users as reasons for classifying air-dryers as unsuitable for use in healthcare settings.11 It also concluded three important points about paper towels. That they:
- cause less contamination of the washroom environment,
- are superior to electric dryers, and
- should be recommended in settings such as hospitals and clinics where hygiene is critical.
The review authors also recommended cost-benefit analysis prior to purchasing air-dryers given their high initial cost and labour intensity of installation.11 More recent studies have supported the review’s conclusions and reaffirmed the unsuitability of air-dryers in healthcare.6,15-17
Contaminating surrounding areas
Clothing contamination and dispersal of organisms up to a metre into surrounding areas through paper towel or WAD use has also been well studied.14,18 19 This, coupled with WAD-associated noise, resulted in researchers again concluding that WADs pose an environmental and occupational hazard and are unsuitable for patient care areas.16,19
Other researchers stated that paper towels are preferable to WADs; however, noted that dispensers with buttons, cranks or levers increased the opportunity for contamination of washed hands.
As a result, educating users about avoiding accidental dispenser contamination is also important.20 In healthcare organisations, infection control and housekeeping need to work collaboratively to carefully assess design and siting of all paper-towel dispensers and to include routine cleaning of them as part of the daily schedule. 20,21
Later research showed that both JAD and paper-towel hand drying produced ballistic droplets close to the event, although JADs produced more droplets that were also detectable further from their source,22 and greater contamination of adjacent walls. The investigators recommended that potential for environmental and personal contamination should also be included in selection of a hand-drying method.22
Additional research15 confirmed that WADs and JADs produced greater airborne dissemination and increased the risk of cross-contamination compared to paper towels. Air-dryers were again deemed unsuitable for healthcare settings.
The debate continues
The debate is ongoing, with reports of JAD-related air bacterial counts 27-fold greater than paper towels.15 This is particularly concerning given the higher microbial load that can be dispersed when hands are wet or incompletely dry.6
Healthcare settings would be wise to mitigate these risks and variability in hand hygiene compliance by only making paper towels available throughout their entire organisation until such time as well-designed, independent, research is undertaken in real rather than experimental settings using healthcare participants rather than volunteers.
1. Pittet D, Allegranzi B, Storr J, Donaldson L. ‘Clean Care is Safer Care’: the Global Patient Safety Challenge 2005-2006. International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases. 2006;10(6):419-424.
2. Pittet D, Boyce JM, Allegranzi B. Hand hygiene : a handbook for medical professionals. 2017.
3. Pittet D, Donaldson L. Clean Care is Safer Care: the first global challenge of the WHO World Alliance for Patient Safety. Infection control and hospital epidemiology : the official journal of the Society of Hospital Epidemiologists of America. 2005;26(11):891-894.
4. Ansari SA, Springthorpe VS, Sattar SA, Tostowaryk W, Wells GA. Comparison of cloth, paper, and warm air drying in eliminating viruses and bacteria from washed hands. American Journal of Infection Control. 1991;19(5):243-249.
5. Gustafson DR, Vetter EA, Larson DR, et al. Effects of 4 hand-drying methods for removing bacteria from washed hands: a randomized trial. Mayo Clin Proc. 2000;75(7):705-708.
6. Best EL, Redway K. Comparison of different hand-drying methods: the potential for airborne microbe dispersal and contamination. J Hosp Infect. 2015;89(3):215-217.
7. Snelling AM, Saville T, Stevens D, Beggs CB. Comparative evaluation of the hygienic efficacy of an ultra-rapid hand dryer vs conventional warm air hand dryers. J Appl Microbiol. 2011;110(1):19-26.
8. Pittet D, Allegranzi B, Boyce J. The World Health Organization Guidelines on Hand Hygiene in Health Care and Their Consensus Recommendations. Infection Control & Hospital Epidemiology. 2009;30(7):611-622.
9. World Health Organization. WHO Guidelines on Hand Hygiene in Health Care. Geneva: World Health Organization; 200
10. Yamamoto Y, Ugai K, Takahashi Y. Efficiency of hand drying for removing bacteria from washed hands: comparison of paper towel drying with warm air drying. Infect Control Hosp Epidemiol. 2005;26(3):316-320.
11. Huang C, Ma W, Stack S. The hygienic efficacy of different hand-drying methods: a review of the evidence. Mayo Clin Proc. 2012;87(8):791-798.
12. Wilcox MH, Best EL, Parnell P. Pilot study to determine whether microbial contamination levels in hospital washrooms are associated with hand-drying method. Journal of Hospital Infection. 2017;97(2):201-203.
13. Matthews JA, Newsom SWB. Hot air electric hand driers compared with paper towels for potential spread of airborne bacteria. Journal of Hospital Infection. 1987;9(1):85-88.
14. Taylor JH, Brown KL, Toivenen J, Holah JT. A microbiological evaluation of warm air hand driers with respect to hand hygiene and the washroom environment. J Appl Microbiol. 2000;89(6):910-919.
15. Best EL, Parnell P, Wilcox MH. Microbiological comparison of hand-drying methods: the potential for contamination of the environment, user, and bystander. J Hosp Infect. 2014;88(4):199-206.
16. Berkowitz S. Hand dryer noise in public restrooms exceeds 80 dBA at 10 ft (3 m). Noise and Health. 2015;17(75):90-92.
17. Alharbi SA, Salmen SH, Chinnathambi A, et al. Assessment of the bacterial contamination of hand air dryer in washrooms. Saudi J Biol Sci. 2016;23(2):268-271.
18. Meers PD, Leong KY. Hot-air hand driers. Journal of Hospital Infection. 1989;14(2):169-171.
19. Ngeow YF, Ong HW, Tan P. Dispersal of bacteria by an electric air hand dryer. Malays J Pathol. 1989;11:53-56.
20. Harrison WA, Griffith CJ, Michaels B, Ayers T. Technique to determine contamination exposure routes and the economic efficiency of folded paper-towel dispensing. Am J Infect Control. 2003;31(2):104-108.
21. Harrison WA, Griffith CJ, Ayers T, Michaels B. Bacterial transfer and cross-contamination potential associated with paper-towel dispensing. Am J Infect Control. 2003;31(7):387-391.
22. Margas E, Maguire E, Berland CR, Welander F, Holah JT. Assessment of the environmental microbiological cross contamination following hand drying with paper hand towels or an air blade dryer. J Appl Microbiol. 2013;115(2):572-582.
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