Hand washing

Hand washing has many significant health benefits, including minimizing the spread of influenza, coronavirus, and other infectious diseases;[16][17] preventing infectious causes of diarrhea;[18] decreasing respiratory infections;[19] and reducing infant mortality rate at home birth deliveries.[20] A 2013 study showed that improved hand washing practices may lead to small improvements in the length growth in children under five years of age.[21] In developing countries, childhood mortality rates related to respiratory and diarrheal diseases can be reduced by introducing simple behavioral changes, such as hand washing with soap. This simple action can reduce the rate of mortality from these diseases by almost 50%.[22] Interventions that promote hand washing can reduce diarrhoea episodes by about a third, and this is comparable to providing clean water in low income areas.[23] 48% of reductions in diarrhoea episodes can be associated with hand washing with soap.[24]

Handwashing with soap is the single most effective and inexpensive way to prevent diarrhea and acute respiratory infections (ARI), as automatic behavior performed in homes, schools, and communities worldwide. Pneumonia, a major ARI, is the number one cause of mortality among children under five years old, taking the lives of an estimated 1.8 million children per year. Diarrhea and pneumonia together account for almost 3.5 million child deaths annually.[25] According to UNICEF, turning handwashing with soap before eating and after using the toilet into an ingrained habit can save more lives than any single vaccine or medical intervention, cutting deaths from diarrhea by almost half and deaths from acute respiratory infections by one-quarter. Hand washing is usually integrated with other sanitation interventions as part of water, sanitation, and hygiene (WASH) programmes. Hand washing also protects against impetigo which is transmitted through direct physical contact.[26]

A small detrimental effect of handwashing is that frequent hand washing can lead to skin damage due to the drying of the skin.[8] A 2012 Danish study found that excessive hand washing can lead to an itchy, flaky skin condition known as hand eczema or hand dermatitis, which is especially common among health-care workers.[27] Too frequent hand washing is also seen as one of the symptoms of obsessive-compulsive disorder (OCD).

There are five critical times during the day where washing hands with soap is important to reduce fecal-oral transmission of disease: after using the toilet (for urination, defecation, menstrual hygiene), after cleaning a child's bottom (changing nappies), before feeding a child, before eating and before/after preparing food or handling raw meat, fish, or poultry.[28] Other occasions when correct handwashing technique should be practiced in order to prevent the transmission of disease include before and after treating a cut or wound; after sneezing, coughing, or blowing your nose; after touching animal waste or handling animals; and after touching garbage.[29][30]

In many countries, there is a low rate of hand washing with soap. A study of hand washing in 54 countries in 2015 found that on average, 38.7% of households practiced hand washing with soap.[31]

A 2014 study showed that Saudi Arabia had the highest rate of 97 percent; the United States near the middle with 77 percent; and China with the lowest rate of 23 percent.[32]

Several behavior change methodologies now exist to increase uptake of the behavior of hand washing with soap at the critical times.[33]

Group hand washing for school children at set times of the day is one option in developing countries to engrain hand washing in children's behaviors.[34] The "Essential Health Care Program" implemented by the Department of Education in the Philippines is an example of at scale action to promote children's health and education.[35] Deworming twice a year, supplemented with washing hands daily with soap, brushing teeth daily with fluoride, is at the core of this national program. It has also been successfully implemented in Indonesia.[36]

Removal of microorganisms from skin is enhanced by the addition of soaps or detergents to water.[37] Soap and detergents are surfactants that kill microorganisms by disorganizing their membrane lipid bilayer and denaturing their proteins. It also emulsifies oils, enabling them to be carried away by running water.[38]

Solid soap, because of its reusable nature, may hold bacteria acquired from previous uses.[39] A small number of studies which have looked at the bacterial transfer from contaminated solid soap have concluded transfer is unlikely as the bacteria are rinsed off with the foam.[40] The CDC still states "liquid soap with hands-free controls for dispensing is preferable".[41]

Antibacterial soaps have been heavily promoted to a health-conscious public. To date, there is no evidence that using recommended antiseptics or disinfectants selects for antibiotic-resistant organisms in nature.[42] However, antibacterial soaps contain common antibacterial agents such as triclosan, which has an extensive list of resistant strains of organisms. So, even if antibiotic resistant strains aren't selected for by antibacterial soaps, they might not be as effective as they are marketed to be. Besides the surfactant and skin-protecting agent, the sophisticated formulations may contain acids (acetic acid, ascorbic acid, lactic acid) as pH regulator, antimicrobially active benzoic acid and further skin conditioners (aloe vera, vitamins, menthol, plant extracts).[43]

A 2007 meta-analysis from the University of Oregon School of Public Health indicated that plain soaps are as effective as consumer-grade anti-bacterial soaps containing triclosan in preventing illness and removing bacteria from the hands.[44] Dissenting, a 2011 meta-analysis in the Journal of Food Protection argued that when properly formulated, triclosan can grant a small but detectable improvement, as can chlorhexidine gluconate, iodophor, or povidone.[45][46]

Hot water that is still comfortable for washing hands is not hot enough to kill bacteria. Bacteria grow much faster at body temperature (37 °C). WHO considers warm soapy water to be more effective than cold, soapy water at removing natural oils which hold soils and bacteria.[47] But CDC mentions that warm water causes skin irritations more often and its ecological footprint is more significant.[1] Water temperatures from 4 to 40 °C do not differ significantly regarding removal of microbes. The most important factor is proper scrubbing.[48]

Contrary to popular belief, scientific studies have shown that using warm water has no effect on reducing the microbial load on hands.[48][49]

Hand disinfection procedure according to the German standard DIN EN 1500

A hand sanitizer or hand antiseptic is a non-water-based hand hygiene agent. In the late 1990s and early part of the 21st century, alcohol rub non-water-based hand hygiene agents (also known as alcohol-based hand rubs, antiseptic hand rubs, or hand sanitizers) began to gain popularity. Most are based on isopropyl alcohol or ethanol formulated together with a thickening agent such as Carbomer (polymer of acrylic acid) into a gel, or a humectant such as glycerin into a liquid, or foam for ease of use and to decrease the drying effect of the alcohol.[50] Adding diluted hydrogen-peroxide increases further the antimicrobial activity.[51]

Hand sanitizers containing a minimum of 60 to 95% alcohol are efficient germ killers. Alcohol rub sanitizers kill bacteria, multi-drug resistant bacteria (MRSA and VRE), tuberculosis, and some viruses (including HIV, herpes, RSV, rhinovirus, vaccinia, influenza,[52] and hepatitis) and fungi. Alcohol rub sanitizers containing 70% alcohol kill 99.97% (3.5 log reduction, similar to 35 decibel reduction) of the bacteria on hands 30 seconds after application and 99.99% to 99.999% (4 to 5 log reduction) of the bacteria on hands 1 minute after application.[53]

Hand sanitizers are most effective against bacteria and less effective against some viruses. Alcohol-based hand sanitizers are almost entirely ineffective against norovirus (or Norwalk) type viruses, the most common cause of contagious gastroenteritis.[54]

In a 2020 Cochrane review comparing rinse-free hand washing to conventional soap and water techniques and the subsequent impact on school absenteeism found a small but beneficial effect on rinse-free hand washing on illness related absenteeism.[55]

Enough hand antiseptic or alcohol rub must be used to thoroughly wet or cover both hands. The front and back of both hands and between and the ends of all fingers must be rubbed for approximately 30 seconds until the liquid, foam or gel is dry. Finger tips must be washed well too, rubbing them in both palms.[56]

US Centers for Disease Control and Prevention recommend hand washing over hand sanitizer rubs, particularly when hands are visibly dirty.[57] The increasing use of these agents is based on their ease of use and rapid killing activity against micro-organisms; however, they should not serve as a replacement for proper hand washing unless soap and water are unavailable.

Frequent use of alcohol-based hand sanitizers can cause dry skin unless emollients and/or skin moisturizers are added to the formula. The drying effect of alcohol can be reduced or eliminated by adding glycerin and/or other emollients to the formula.[50] In clinical trials, alcohol-based hand sanitizers containing emollients caused substantially less skin irritation and dryness than soaps or antimicrobial detergents. Allergic contact dermatitis, contact urticaria syndrome or hypersensitivity to alcohol or additives present in alcohol hand rubs rarely occur.[58] The lower tendency to induce irritant contact dermatitis became an attraction as compared to soap and water hand washing.

Despite their effectiveness, non-water agents do not cleanse the hands of organic material, but simply disinfect them. It is for this reason that hand sanitizers are not as effective as soap and water at preventing the spread of many pathogens, since the pathogens remain on the hands.

Alcohol-free hand sanitizer efficacy is heavily dependent on the ingredients and formulation, and historically has significantly under-performed alcohol and alcohol rubs. More recently, formulations that use benzalkonium chloride have been shown to have persistent and cumulative antimicrobial activity after application,[59] unlike alcohol, which has been shown to decrease in efficacy after repeated use, probably due to progressive adverse skin reactions.[60]

Hand washing using hand sanitizing wipes is an alternative during traveling in the absence of soap and water.[61] Alcohol-based hand sanitizer should contain at least 60% alcohol.[62]

Many people in low-income communities cannot afford soap and use ash or soil instead. The World Health Organization recommended ash or sand as an alternative to soap when soap is not available.[63] Evidence quality to support the use of ash to wash hands is poor and it is not clear if washing hands with ash is effective at reducing viral or bacterial spreading compared to washing with mud, not washing, or with washing with water alone.[7] One concern is that if the soil or ash is contaminated with microorganisms it may increase the spread of disease rather than decrease it,[64] however, there is also no clear evidence to determine the level of risk.[7] Like soap, ash is also a disinfecting agent because in contact with water, it forms an alkaline solution.[65]

Various low-cost options can be made to facilitate hand washing where tap-water and/or soap is not available e.g. pouring water from a hanging jerrycan or gourd with suitable holes and/or using ash if needed in developing countries.[68]

In situations with limited water supply (such as schools or rural areas in developing countries), there are water-conserving solutions, such as "tippy-taps" and other low-cost options.[69] A tippy-tap is a simple technology using a jug suspended by a rope, and a foot-operated lever to pour a small amount of water over the hands and a bar of soap.[70]

Low-cost hand washing technologies for households may differ from facilities for multiple users.[71] For households, options include tippy taps, bucket/container with tap, conventional tap with/without basin, valve/tap fitted to bottles, bucket and cup, camp sink.[71] Options for multiple users include: adapting household technologies for multiple users, water container fitted to a pipe with multiple taps, water container fitted to a pipe with holes.[71]

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  Schoolchildren washing their hands before eating lunch in 1940s United States
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  Tanzanian drawing of a tippy tap with soap for hand washing at a school
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  Students washing their hands with a simple handwasher at a school in Zimbabwe
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  Hand washer

Several companies around the globe have developed technologies that aim to improve the hand washing process. Among the different inventions, there are eco-friendly devices that use 90% less water and 60% less soap compared to hand washing under a faucet.[72][73] Another device uses light-based rays to detect contaminants on the hands after they have been washed.[74]

Certain environments are especially sensitive to the transmission of pathogenic microorganisms, like health care and food production. Organizations attempting to prevent infection transmission in these environments have started using programmed washing cycles that provide sufficient time for scrubbing the hands with soap and rinsing them with water. Combined with AI-powered software, these technological advancements turn the hand-washing process into digital data, allowing individuals to receive insights and improve their hand hygiene practices.[75][76][77]

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  A nurse uses a smart hand washing device

Effective drying of the hands is an essential part of the hand hygiene process. Therefore, the proper drying of hands after washing should be an integral part of the hand hygiene process in health care.[2]

The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) are clear and straightforward concerning hand hygiene, and recommend paper towels and hand dryers equally. Both have stressed the importance of frequent and thorough hand washing followed by their complete drying as a means to stop the spread of germs, like coronavirus. Specifically, the World Health Organization recommends that everyone “frequently clean [their] hands…” and “dry [them] thoroughly by using paper towels or a warm air dryer.” The Centers for Disease Control and Prevention report that, “Both [clean towels or air hand dryers] are effective ways to dry hands.”

A study in 2020 found that hand dryers and paper towels were both found to be equally hygienic hand-drying solutions.[78]

However, there is some debate over the most effective form of drying in public toilets. A growing volume of research suggests paper towels are much more hygienic than the electric hand dryers found in many public toilets. A review in 2012 concluded that "From a hygiene standpoint, paper towels are superior to air dryers; therefore, paper towels should be recommended for use in locations in which hygiene is paramount, such as hospitals and clinics."[2]

Jet-air dryers were found to be capable of blowing micro-organisms from the hands and the unit and potentially contaminating other users and the environment up to 2 metres away.[79] In the same study in 2008 (sponsored by the paper-towel industry the European Tissue Symposium), use of a warm-air hand dryer spread micro-organisms only up to 0.25 metres from the dryer, and paper towels showed no significant spread of micro-organisms. No studies have found a correlation to hand dryers and human health, however, making these findings inconsequential.

Making hand washing facilities accessible (inclusive) to everyone is crucial to maintain hand washing behavior.[71]^:27 Considerations for accessibility include age, disability, seasonality (with rains and muddiness), location and more. Important aspects for good accessibility include: Placement of the technology, paths, ramps, steps, type of tap, soap placement.[71]^:27

Medical hand-washing is for a minimum of 15 seconds, using generous amounts of soap and water or gel to lather and rub each part of the hands.[83] Hands should be rubbed together with digits interlocking. If there is debris under fingernails, a bristle brush may be used to remove it. Since germs may remain in the water on the hands, it is important to rinse well and wipe dry with a clean towel.[84] After drying, the paper towel should be used to turn off the water (and open any exit door if necessary). This avoids re-contaminating the hands from those surfaces.

The purpose of hand-washing in the health-care setting is to remove pathogenic microorganisms ("germs") and avoid transmitting them. The New England Journal of Medicine reports that a lack of hand-washing remains at unacceptable levels in most medical environments, with large numbers of doctors and nurses routinely forgetting to wash their hands before touching patients, thus transmitting microorganisms.[85] One study showed that proper hand-washing and other simple procedures can decrease the rate of catheter-related bloodstream infections by 66 percent.[86]

The World Health Organization has published a sheet demonstrating standard hand-washing and hand-rubbing in health-care sectors.[87] The draft guidance of hand hygiene by the organization can also be found at its website for public comment.[47] A relevant review was conducted by Whitby et al.[88] Commercial devices can measure and validate hand hygiene, if demonstration of regulatory compliance is required.

The World Health Organization has "Five Moments" for washing hands:

• before patient care
• after environmental contact
• after exposure to blood/body fluids
• before an aseptic task, and
• after patient care.

The addition of antiseptic chemicals to soap ("medicated" or "antimicrobial" soaps) confers killing action to a hand-washing agent. Such killing action may be desired before performing surgery or in settings in which antibiotic-resistant organisms are highly prevalent.[89]

To 'scrub' one's hands for a surgical operation, it is necessary to have a tap that can be turned on and off without touching it with the hands, some chlorhexidine or iodine wash, sterile towels for drying the hands after washing, and a sterile brush for scrubbing and another sterile instrument for cleaning under the fingernails. All jewelry should be removed. This procedure requires washing the hands and forearms up to the elbow, usually 2–6 minutes. Long scrub-times (10 minutes) are not necessary. When rinsing, water on the forearms must be prevented from running back to the hands. After hand-washing is completed, the hands are dried with a sterile cloth and a surgical gown is donned.

To reduce the spread of germs, it is better to wash the hands or use a hand antiseptic before and after tending to a sick person.

For control of staphylococcal infections in hospitals, it has been found that the greatest benefit from hand-cleansing came from the first 20% of washing, and that very little additional benefit was gained when hand cleansing frequency was increased beyond 35%.[90] Washing with plain soap results in more than triple the rate of bacterial infectious disease transmitted to food as compared to washing with antibacterial soap.[91]

Comparing hand-rubbing with alcohol-based solution with hand washing with antibacterial soap for a median time of 30 seconds each showed that the alcohol hand-rubbing reduced bacterial contamination 26% more than the antibacterial soap.[92] But soap and water is more effective than alcohol-based hand rubs for reducing H1N1 influenza A virus[93] and Clostridium difficile spores from hands.[94]

Interventions to improve hand hygiene in healthcare settings can involve education for staff on hand washing, increasing the availability of alcohol-based hand rub, and written and verbal reminders to staff.[95] There is a need for more research into which of these interventions are most effective in different healthcare settings.[95]

Poster used in Africa for raising awareness about hand washing after using the toilet with simple low-cost hand washing device

The promotion and advocacy of hand washing with soap can influence policy decisions, raise awareness about the benefits of hand washing and lead to long-term behavior change of the population.[98] For this to work effectively, monitoring and evaluation are necessary. A systematic review of 70 studies found that community-based approaches are effective at increasing hand washing in LMICs, while social marketing campaigns are less effective.[99]

One example for hand washing promotion in schools is the "Three Star Approach" by UNICEF that encourages schools to take simple, inexpensive steps to ensure that students wash their hands with soap, among other hygienic requirements. When minimum standards are achieved, schools can move from one to ultimately three stars.[100] Building hand washing stations can be a part of hand washing promotion campaigns that are carried out to reduce diseases and child mortality.

Global Hand washing Day is another example of an awareness-raising campaign that is trying to achieve behavior change.[101]

As a result of the ongoing COVID-19 pandemic, UNICEF promoted the adoption of a hand washing emoji.[102]

Designing hand washing facilities that encourage use can use the following aspects:[71]

• Nudges, cues and reminders
• Hand washing facilities should be placed at convenient locations to encourage people to use them regularly and at the right times; they should be attractive and well maintained.

Few studies have considered the overall cost effectiveness of hand washing in developing countries in relationship to DALYs averted. However, one review suggests that promoting hand washing with soap is significantly more cost-effective than other water and sanitation interventions.[103]

The phrase "washing one's hands of" something, means declaring one's unwillingness to take responsibility for the thing or share complicity in it. It originates from the bible passage in Matthew where Pontius Pilate washed his hands of the decision to crucify Jesus Christ, but has become a phrase with a much wider usage in some English communities.

In Shakespeare's Macbeth, Lady Macbeth begins to compulsively wash her hands in an attempt to cleanse an imagined stain, representing her guilty conscience regarding crimes she had committed and induced her husband to commit.

It has also been found that people, after having recalled or contemplated unethical acts, tend to wash hands more often than others, and tend to value hand washing equipment more. Furthermore, those who are allowed to wash their hands after such a contemplation are less likely to engage in other "cleansing" compensatory actions, such as volunteering.[105][106]

Religions prescribe hand washing for both hygienic and symbolic purposes.[15]

Symbolic hand washing, using water but no soap to wash hands, is a part of ritual hand washing featured in many religions, including the Baháʼí Faith, Hinduism, tevilah and netilat yadayim in Judaism, Cantharus and Lavabo in Christianity,[10][11] and Wudhu in Islam.[15]

Religions also prescribe hygienic hand washing, especially after certain actions. Hinduism, Judaism, Christianity,[10][11][107] and Islam mandate washing of hands after using the toilet. In Hinduism, Buddhism, Sikhism, Judaism, certain denominations of Christianity,[13][108] and Islam mandate washing of hands before and after every meal.[15]