title: Microbiological comparison of hand-drying methods: the potential for contamination of the environment, user, and bystander.
abstract: BACKGROUND
  The efficiency of hand drying is important in preventing pathogen spread, but knowledge surrounding which drying methods contribute least towards contamination of the environment and users is limited.
  
  
  OBJECTIVE
  To compare the propensity of three common hand-drying methods (jet air, warm air dryers, and paper towels) to contaminate the environment, users, and bystanders.
  
  
  METHODS
  Hands were coated in lactobacilli to simulate poorly washed, contaminated hands, and dried. The investigation comprised 120 air-sampling tests (60 tests and 60 controls), divided into close and 1m proximity from the drying process. Separate tests used hands coated in paint to visualize droplet dispersal.
  
  
  RESULTS
  Air bacterial counts in close proximity to hand drying were 4.5-fold higher for the jet air dryer (70.7 cfu) compared with the warm air dryer (15.7 cfu) (P=0.001), and 27-fold higher compared with use of paper towels (2.6 cfu) (P<0.001). Airborne counts were also significantly different during use of towel drying versus warm air dryer (P=0.001). A similar pattern was seen for bacterial counts at 1m away. Visualization experiments demonstrated that the jet air dryer caused the most droplet dispersal.
  
  
  CONCLUSIONS
  Jet air and warm air dryers result in increased bacterial aerosolization when drying hands. These results suggest that air dryers may be unsuitable for use in healthcare settings, as they may facilitate microbial cross-contamination via airborne dissemination to the environment or bathroom visitors.
authors.affiliation: Microbiology Department, Old Medical School, Leeds General Infirmary, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: E L
authors.initials: EL
authors.lastname: Best
authors.affiliation: Microbiology Department, Old Medical School, Leeds General Infirmary, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
authors.forename: P
authors.initials: P
authors.lastname: Parnell
authors.affiliation: Microbiology Department, Old Medical School, Leeds General Infirmary, Leeds Teaching Hospitals NHS Trust, Leeds, UK; University of Leeds, Leeds, UK. Electronic address: mark.wilcox@leedsth.nhs.uk.
authors.forename: M H
authors.initials: MH
authors.lastname: Wilcox
mesh_terms: D000391:Air Microbiology; D015169:Colony Count, Microbial; D003428:Cross Infection / Q000517:prevention & control; D004784:Environmental Monitoring / Q000379:methods; D006225:Hand / Q000382:microbiology*; D006235:Hand Disinfection / Q000379:methods*; D006801:Humans; D007778:Lactobacillus / Q000302:isolation & purification
keywords: Air driers; Bacteria; Droplet dispersal; Environmental contamination; Hand drying; Hand hygiene