Hand hygiene is central to public health and safe healthcare practice, and its impact on the control and spread of infections is even more apparent in light of the COVID-19 pandemic. Research shows that hand hygiene is the single most important strategy for preventing and reducing the spread of microorganisms (Schweizer et al, 2014; Luangasanatip et al, 2015); and occupies a unique position within the field of healthcare and patient safety, in that it is universally relevant to staff and patients at every healthcare encounter. The important role of hand hygiene in preventing the transmission of microorganisms has been especially highlighted most recently following the global pandemic of the coronavirus causing COVID-19, which was initially identified in Wuhan, China, in late December 2019. The ability of hand hygiene, including hand washing or the use of alcohol-based hand sanitisers, to prevent infections is related to the reduction in the number of viable pathogens that transiently contaminate the hands. Following the initial outbreak, COVID-19-specific infection prevention measures were rapidly introduced, with hand hygiene for infection prevention forming a crucial part of the international response to the global emergence of COVID-19. Interestingly, the focus and effort of COVID-19 public health campaigns and health professional education has been on hand washing, with no or little emphasis on hand drying. Historically, the frequency of hand hygiene among healthcare staff and the wider public has been suboptimal and while compliance with hand-hygiene practices has improved, especially in healthcare settings and hospitals where promotion has been implemented (Schweizer et al, 2014; Luangasanatip et al, 2015), it remains that behaviours fall short of the necessary expectations. This is particularly true for hand drying, as strategies to improve behavioural compliance with hand hygiene remain limited in their effectiveness in that they fail to consider this vital, although much neglected, aspect of hand-hygiene practice.
Hand drying is imperative in that it not only maintains and supports skin integrity (Jungbauer et al, 2004a; 2004b; Snelling et al, 2011; Behroozy and Keegel, 2014; Jensen et al, 2015), but also decreases microbial count on the skin surface (Merry et al, 2001; Snelling et al, 2011; Jensen et al, 2015). Human skin is a relatively dry environment, and this helps to limit the types and numbers of microorganisms that can survive on it. Thus if hands are wet and remain wet for a considerable period of time, this has a significant impact on skin condition and on microbial load and transfer. This article draws on a historical trajectory of research among authors in the area of infection prevention (see for example: Gammon, 1998; Gammon and Hunt, 2018a; 2018b; 2019; Gammon et al, 2019a; 2019b) in order stimulate debate regarding the significance of hand drying in the process of hand hygiene.
Implications for health professionals and practice
Residual moisture on the hands and the amount of time hands are wet or exposed to wetness, are factors of importance in terms of hand hygiene and infection prevention. Water exposure can cause swelling and shrinking of the stratum corneum and can lead to hand dermatitis. The nature of clinical practice means that the hands of healthcare staff are frequently exposed to wetness, often referred to as wet work, increasing the risk of skin irritation and microbial transmission. The literature defines wet work as activities where healthcare staff have to immerse their hands in liquids for more than 2 hours per shift, wear waterproof (occlusive) gloves for a corresponding amount of time, or wash their hands more than 20 times per shift. In similar ways, Fartasch (2016) defined wet work as unprotected exposure to humid environments/water, high frequencies of hand-washing procedures or prolonged glove occlusion, all of which is believed to cause irritant contact dermatitis in a variety of occupations. Further studies note the effect that wet hands have on the skin condition, and research has found that wet work exposure is a major risk factor for hand dermatitis and irritation (Behroozy and Keegel, 2014; Papadatou et al, 2018) and increases the risk of microbial transmission (Patrick et al, 1997; Ataee et al, 2017). Therefore, this article will focus on two issues of importance with regards to hand drying and the implications for healthcare staff and practice: microbial transmission and skin irritation.
Wet hands increase the likelihood of microbial transmission
There is an increased likelihood of microbial transmission when hands are wet or damp, rather than dry (Gould and Ream, 1994; Patrick et al, 1997; Merry et al, 2001; Ataee et al, 2017). Microorganisms of the normal skin flora are adapted to live in the environment, while other microbes can die within a matter of minutes to hours of contact. Significantly, if microorganisms are suspended in a fluid (eg water, blood, saliva or milk) when in contact with the skin, it affects the rate at which drying occurs, which extends the time microbes survive on the skin. Microorganisms within droplets of moisture on the surface of the hands may consequently be afforded a degree of protection from perishing on a dry surface, and the longer they can survive there, the greater the chance of them being transmitted and cross-infection occurring. In this way, Merry et al (2001) stated that microbial transfer and touch contamination greatly increases when hands are wet and significantly reduce with thorough hand drying. In their study, Ataee et al (2017) suggested that the released amount of microbial flora from wet hands is more than 10 times that from dry hands. Patrick et al (1997) noted that the single most important determinant of the number of microorganisms translocated from hands to equipment or environmental surfaces, was the extent of residual moisture remaining on hands after washing. They established a clear correlation between residual moisture on the hands and microbial transmission with touch contact.
The effects of wet hands on skin integrity
Health professionals are at high risk of developing occupational hand dermatitis as a consequence of frequent exposure to ‘wet work’, soaps, detergents and antiseptics (Jungbauer et al, 2004a; 2004b; Snelling et al, 2011; Behroozy and Keegel, 2014) owing to the nature of mandatory hygiene procedures, coupled with ineffective hand drying and/or the use of hand gloves. The symptoms of hand dermatitis include dryness, irritation, itching, cracking and bleeding, which are made worse by the removal of natural skin moisturisers, and in turn can lead to altered and higher numbers of microbes colonising the skin surface. Among healthcare staff, nurses are particularly at risk of hand dermatitis, where the work performed requires many cycles of hand washing per hour. It is estimated that around 1000 nurses develop work-related irritant contact dermatitis each year in the UK (Behroozy and Keegel, 2014).Visser et al (2014) measured the effects of wet work exposure among nurses and found that, in year 1 of the study, the prevalence of developing hand eczema was 23%, in year 2 it was 25% and in year 3 prevalence increased to 31%. In an earlier prevalence study of irritant contact dermatitis in health professionals by Larson (2001), the figures ranged between 10 and 45%. The consequence, aside from the health impact for the health professional, is an increased likelihood of noncompliance to hand-hygiene practice recommendations (Gould and Ream, 1994) and consequently cross-infection.
In addition to regular hand washing, healthcare staff are exposed to further risks of skin irritation (eg glove use, antiseptics and detergents) (Antonov et al, 2013; Fartasch, 2016), which can result in wet hands and skin breakdown (Antonov et al, 2013; Tiedemann et al, 2016; Fartasch, 2016). The use of gloves, which can generate heat and moisture that collects as a result of the occlusive effect of the gloves, can facilitate the growth of microorganisms and the activation of other potential irritants, thus further increasing the potential of environmental contamination and cross-infection (Jungbauer et al, 2004a; 2004b; Behroozy and Keegel, 2014). In their study, Tiedemann et al (2016) concluded that studies investigating the combined effect of occlusion and exposure to detergents indicate that occlusion significantly increases damage to the skin barrier. In similar ways, Hamnerius et al (2018) noted that hand washing with soap and use of disposable gloves was associated with the occurrence of self-reported hand irritation in a dose-dependent way. Therefore, the use of occlusive protection gloves has to be carefully considered to avoid over use and interventional studies such as Gasparini et al (2019), have been shown to be beneficial with regards to raising awareness of appropriate glove use and hand washing among staff.
The significance of hand drying
These two critical factors emphasise the need for hands to be effectively dried as part of the hand-hygiene process and particularly in outbreak situations, when episodes of hand hygiene markedly increase. However, to what extent are hands effectively dried? Research to understand the duration and efficacy of hand drying is limited. Since the wetness of hands greatly influences microbial transmission, drying methods (Mutters and Warnes, 2019) and hand drying efficacy (Gammon and Hunt, 2019) after hand washing should be considered as an essential part of hand-hygiene procedures and recommended for the public during community epidemics and pandemics, such as the COVID-19 pandemic.
Wet or damp hands, as a result of ineffective drying, can lead to skin irritation, which in turn leads to higher numbers of microorganisms colonising the skin and facilitating increased spread. Patrick et al (1997) noted that, by drying the hands thoroughly, the number of microbes transferring by direct contact to skin, food or objects can be reduced by the order of 99%.
Consequently, the duration and efficacy of different drying methods is important in preventing wet hands, maintaining healthy skin integrity and controlling the spread of microorganisms. In their review of the literature, Gammon and Hunt (2019) identified 13 studies assessing the capacity of different hand-drying methods to translocate and disperse microorganisms into the immediate environment and to other persons. Nine of the identified studies noted that jet air dryers and warm air dryers resulted in greater microbial dispersion when compared to paper towels. A recent study by Best et al (2018) investigated options for hand drying in hospital washrooms. They noted multiple examples of significant differences in the extent of surface microbial contamination, with higher levels of contamination being measured in hospital washrooms using a jet air dryers compared with those using paper towels. Best et al (2018) concluded that jet air dryers may not be suitable for settings where microbial cross-contamination risks are high, including hospital settings. Redway and Fawdar (2009) and Hanna et al (1996) suggested that paper towels are more effective in removing all types of microbes on the hands, particularly the fingertips, and that jet air dryers and hot air dryers increased all types of bacteria on the hands. According to Todd et al (2010), drying hands with a towel removes pathogens first by friction during rubbing with the drying material and then by wicking away the moisture into that material. They concluded that the use of paper towels should be encouraged. Conversely research by Ansari et al (1991) and Suen et al (2019), examined the ability of different drying methods to reduce microbial load on the hands and concluded that the use of jet air dryers is the best method to eliminate microbes on hands.
Conclusion
It is clear that dry hands are safer hands. Wet hands are an infection risk, increasing the potential for microbial transmission and dispersion, skin irritation for healthcare staff, harm to patients and environmental contamination. Research demonstrates that effective hand drying contributes to a reduction in the number of microbes on the surface of hands and, therefore, hand drying is integral to the process of hand hygiene, which aims to optimise the removal of potentially pathogenic microorganisms and maintain skin integrity. Hand drying prevents moisture acting as a bridge, allowing microorganisms to be translocated and environmental surfaces contaminated. Understanding this aspect of practice, together with associated risk factors such as glove use and exposure to antiseptics, is crucial in determining the potential for cross-infection and the wellbeing of healthcare staff. Many hand-hygiene educational interventions and public health campaigns present an imbalanced emphasis on the formative steps of handwashing, neglecting the imperative for thorough hand drying. Thus, although there is awareness of the importance of hand hygiene, practice does not convey understanding of the significance of hand-drying duration and efficacy among healthcare staff and the wider public. Indeed, the public health messaging associated with the COVID-19 pandemic has made very little reference to hand drying, if any at all. A holistic approach to hand hygiene must be the ambition so that health professional and public hand-hygiene behaviour becomes embedded and is sustained.