Hand drying should be an essential part of the hand hygiene process in health care.
11,13 However, there appears to be little agreement regarding the most hygienic method of hand drying. The results of different studies have also been conflicting.
62 Some studies indicated that electric air dryers are of inferior effectiveness when it comes to the issue of hygiene,
39,43,44 whereas others were of a firm opinion that they are a safe and effective means of hand drying.
47,48The large discrepancy among studies may be partly explained by the differences in the experimental protocols used. The degree of wetness is an important factor in determining the number of bacteria detected. Taylor et al
47 claimed that the contact plate results appeared to reflect the degree of wetness after drying rather than the actual number of bacteria on the hands. Some investigators used a long drying time of hot air dryers in their studies, whereas others used a short drying time. For example, Matthews and Newsom
48 used hot air dryers until the study participants had completely dry hands, usually for 1 minute. However, Redway and Fawdar
39 attempted to reproduce people's usual hand-drying practices as closely as possible. In their study, the mean hand-drying times were 10 seconds using paper towels and 20 seconds using hot air dryers. So the significantly poorer hygiene performance of hot air dryers could be due to their low drying efficiency and consequently the greater amount of water remaining on the hands.
Although jet air dryers had drying efficiency similar to paper towels, their hygiene performance was still worse than paper towels.
39 The differences in bacterial numbers after drying with air dryers and paper towels could be due to other factors rather than the percentage of dryness alone. Friction can dislodge microorganisms from the skin surface during both hand washing and drying. Antimicrobial agents in soaps have too little contact time to have bactericidal effects during a single use or with sporadic washings, making friction the most important element in hand drying.
40 It is likely that paper towels work better because they physically remove bacteria from the hands, whereas hot air dryers and jet air dryers cannot.
39 In many instances, however, rubbing hands with hot air dryers to hasten drying would only lead to greater bacterial numbers and airborne dissemination.
49 It might be that rubbing hands causes bacteria to migrate from the hair follicles to the skin surface.
35,44Many studies have found friction to be a key component in hand drying for removing contamination. For example, Sprunt et al
63 and Coates et al
32 reported that bacteria were removed from washed hands by the mechanical abrasive action of drying with paper towels. Taylor et al
47 and Yamamoto et al
49 conducted microbiological testing of the paper towels after use, which indicated that many bacteria were transferred from the hands to paper towels.
Air movement can encourage the dispersal and transmission of bacteria and increase the chance of cross-contamination. Surrounding air in the washroom is recirculated by air dryers. This recirculation may result in the dispersion of infective aerosols already in the atmosphere and those generated by hands being rubbed together for drying.
45 Used air dryers in washrooms are often contaminated and can emit bacteria in their air flow.
39 So, there is a potential risk of persons standing in front of air dryers acquiring the bacteria being dispersed in the air current toward them. The bacteria can be inhaled or can be deposited on the person's body or clothes, thus making him/her a potential mobile source of infection.
54Overall, the hygienic efficacy of the hand-drying method is not only the percentage of dryness of the hands but also the removal of bacteria from washed hands and the prevention of cross-contamination. Hot air dryers are generally not recommended for use in health care settings because such dryers are relatively slow and noisy and their hygiene performance is questionable.
44 Cloth roller towels are not recommended because they can become common-use towels at the end of the roll and can be a source of pathogen transfer to clean hands. Recently, jet air dryers have undergone independent certification within the food safety arena in Australia, attesting to their increased hygiene benefits as opposed to the traditional hot air-drying method.
64 However, the criteria and process of obtaining this type of certification remain questionable. The health and safety aspects of jet air dryers for use in locations where hygiene is paramount should still be carefully examined by the scientific community. Therefore, this makes paper towel drying, during which little air movement is generated, the most hygienic option of hand-drying methods in health care.
39The principles of hand hygiene are universal. They do not change because of sex, skin color, or hand size.
40 On the basis of our review, drying hands thoroughly with single-use, disposable paper towels is the preferred method of hand drying in terms of hand hygiene. This conclusion raises the question of what types of paper towel should be used for hand drying. Does the quality of paper towel have an effect on hand hygiene adherence? When recycled paper is used for hand drying, what kinds of studies are appropriate to assess the cost benefit of using recycled paper? Many questions remain unanswered. Different types of paper towel may have different absorption characteristics, which can influence their capacity to remove bacteria from washed hands.
45 The quality of paper towel is important because poor-quality towels can damage skin by abrasion and ineffective drying.
41,65 Recycled paper would be more acceptable in the future because it can contribute to environment sustainability. Such research may have the potential to improve hand hygiene practice and sustainable development significantly.
The maintenance of a clean environment around paper towels is also important. Paper towels deposited in bins could act as a bacteriologic reservoir if disposal is not managed properly.
47 Regular sanitary cleaning of washrooms is the only way to reduce bacteria numbers and prevent cross-contamination.
51 Moreover, paper towels require delivery to users from dispensers. The risk of potential contamination among dispenser exits, paper towels, and hands should be considered in the design, construction, and use of paper towel dispensers.
66 Architects working in the health care industry should also be aware of these issues when designing equipment for new facilities.
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