Hand Washing:Why, When, and How

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Hand washing is simple, effective, not done enough, and prevents infections. Hand washing is an underused way to stay healthy, doesn’t take much time, effort, or money, and effectively prevents infectious diseases.

In 1847, a Viennese physician noticed that maternity patients died after medical students worked on them after dissecting cadavers. Washing the students’ hands stopped the deaths. In 2009, The Centers for Disease Control and Prevention (CDC) agrees—hand washing is the most effective way to remain healthy. All you need is soap and warm water, or an alcohol-based hand sanitizer that does not need water to be effective. Most people don’t wash correctly, long enough, or often enough[1,2].

Hand washing is effective in a long list of infectious diseases, but particularly in the common cold, influenza, staph (including MRSA)[3], strep, diarrhea and pneumonia in children, in preventing food poisoning with E coli, Salmonella, botulism, Norovirus gastroenteritis (the “cruise-ship” bug), the fecal-oral transmission of Hepatitis A, and with prevention of parasitic diseases such as Cryptosporidiosis, Trichinosis, and Blastocystis. Most recently, there is some doubt about the efficacy of hand washing against the H1N1 virus[4,5]. However, since there are no rigorous studies as yet providing concrete data this is not the case, and H1N1 infects the same was as seasonal flu, the CDC continues to advise hand washing[6].


Why wash

As you go through your daily activities, you accumulate germs on your hands from direct contact with people, contaminated objects, surfaces, foods, dirt (including house dust), and animal waste. Fats and oils are responsible for the adherence of matter to our skin, in which germs are found. By touching new surfaces and objects (such as doorknobs, computer keys steering wheels), you spread the germs. Or you may even infect yourself after touching your face, eyes, nose, or mouth. Dirty hands also cause a number of instances of food-related illness due to infection.

Since the symptoms and signs of a cold and flu (influenza) may be similar, it is sometimes difficult to tell them apart. Colds may be caused by many different viruses, and are mainly self-limiting within a week. True influenza is a specific and much more serious disease, causing great debility, pneumonia in the elderly, and death. In fact, the “flu” is the 7th leading cause of death in this country. Hand washing prevents both illnesses.

An increase in hand washing in children younger than five years old halved the incidence of pneumonia. In children younger than 15 years, diarrhea and impetigo were reduced by 53% and 34% respectively by hand washing[7]. Interestingly there was no difference in disease between children who washed with antibacterial soap or plain soap.

We are talking about more than theory here. A two-year study in Naval recruits showed that hand washing lowered clinic visits for upper respiratory infections by 45%, and was even higher for those who washed more often[8].

The Cochrane Acute Respiratory Infections Group, writing in the British Medical Journal Jan 2008[9], systematically reviewed data from 59 studies, and concluded that physical measures are highly effective in lowering the spread of upper respiratory infections. These included hand washing over 10 times daily, distancing, wearing masksgloves and gowns. The Group, led by Tom Jefferson MD, wrote “the current mainstay of pandemic interventions still seems to be vaccines and antiviral drugs, with no evidence supporting their widespread use.”

In a national telephone survey of 916 people done in August, 2008[10,11], Americans earned a C-minus for their hand hygiene, about the same as they did in the same survey done in 2006. About 46% of people washed in less than 15 seconds (you need 15-20 sec), fewer than 36% washed before eating lunch, and only 56% knew that hand washing was the best way to prevent colds. Only about 80% of people wash after using the toilet.

When to wash

There are critical times to wash your hands, which are more important than intermittent washings, to prevent direct transmission, contamination, and fecal-oral transmission of germs:

• After using the bathroom, including in your own house

• After changing a diaper (wash the diaper-wearer’s hands as well)

• After touching animals and animal waste

• Before and after preparing food, or handling raw meat, poultry, or fish

• Before eating

• Before feeding a child

• After sneezing or coughing into your hands

• Before or after coming into contact with cuts, wounds, or any other open skin

• Before and after contact with a sick or injured person or animal, or someone with diarrhea or loose stools

• After working in the yard

• After a thorough house-cleaning, especially in areas not recently cleaned

• After handling garbage

• Before or after touching or inserting contact lenses

• After leaving public transportation: buses, trains, trolleys, cabs

• After shaking hands with several people

• After sex, especially with a new (or unusual) partner

• After using public restrooms in heavily travelled areas, such as train or bus stations, airports, restaurants, etc.

• Any other situation in which contamination might be important, such as visiting someone in the hospital

If the job you are about to do is especially messy, such as cleaning large amounts of feces, places, objects or bodily fluids known to be contaminated, handling people with known communicable diseases such as infectious diarrhea, extensive animal contact, or working heavily in the yard, wear gloves.

Soap and water, antibacterial soap, and alcohol

Water without any detergent cannot interface chemically with oils, fats, and many proteins in dirt. Substances that are soluble in water are called hydrophilic, and those that are soluble in oil or fat are called hydrophobic. Soap, with two parts, one hydrophilic and the other hydrophobic, connects the water and oil/fat and helps wash it off your hands. In addition to the presence of soap, a high water flow is needed for effective hand washing. Warm water is more efficient than cold in removing oils and fats from hands, because higher temperatures promote the physical associations between soap, oil, and water. At usual hot water temperatures, bacteria are not destroyed by the heat or the soap—it is the removal of the microbes that makes washing effective. There is some effect of soap on bacterial membranes, but the main benefit is removal of the organisms. When using bars of soap, it is common for the bar surface to soften. This layer may remain contaminated after washing, so it is best to wash the soft portion away. For this reason, liquid soap is preferable… except when the liquid soap is allowed to cake on the dispenser.

Using antiseptics or disinfectants doesn’t favor the development of antibiotic-resistant organisms. However, antibacterial soaps contain common antibacterial agents such as triclosan, which has an extensive list of resistant strains of organisms. Laboratory studies suggest that triclosan residues that remain on hands may lead to resistance in the remaining bacteria. Both triclosan and triclocarban in antibacterial soaps have been detected in breast milk, fish and waste water. While there is no direct proof that antibacterial soaps select for antibiotic resistant strains, they are certainly not as effective as their marketing material would have us believe.

Antibacterial soaps don’t do more than regular soap and water[12]. A thorough analysis from the University of Oregon School of Public Health showed that plain soaps are as effective as anti-bacterial soaps in preventing illness and removing bacteria from hands. The American Medical Association and FDA have opposed the widespread use of antibacterial soaps because of lack of evidence they are superior to plain soap and water [13]. An FDA panel of experts assembled in 2005 also voted 11-to-1 that antimicrobial soap offers no improvement over ordinary soap. The soap and detergent industry maintains that antiseptic soap products have no effect upon antimicrobial resistance and should be recognized as superior[14]. It is still believed that some bacteria on the skin will survive antibacterial soap and become resistant. Even so, Americans spend over $200 million annually on antibacterial wipes, but despite hundreds of new products annually it has had no impact on prevalence of any infectious disease. The effective way to get rid of germs is by washing hands.

Hand antiseptic rubs

Alcohol-based hand rubs, also called hand sanitizers, are popular, convenient, and effective. They contain isopropyl, ethyl, or n-propyl alcohol with a thickening agent, and are available as a gel, foam, or liquid. Emollients and moisturizers are added to prevent drying.

Hand sanitizers containing a minimum of 60 to 95% alcohol are efficient germ killers. Alcohol rub sanitizers kill bacteria by denaturing protein and rupturing their membranes. Microbes killed by alcohol sanitizers include multi-drug resistant bacteria (MRSA and vancomycin-resistant enterococcus, tuberculosis, and viruses (including HIV, herpes, RSV, rhinovirus, vaccinia, influenza, H1N1 Swine flu, hepatitis) and fungus.

The rising appeal of these agents is based on their ease of use and rapid killing activity against micro-organisms.

How to wash

Soap and water

• Remove all jewelry before you wash, and wash the underside of rings, etc.

• Wet your hands with warm—not hot—running water, apply liquid or clean bar soap evenly over both hands. This should take at least one minute.

• Lather and rub your hands vigorously together for at least 20 seconds. This is about the time it takes for you to sing Happy Birthday To You or Row, Row, Row, Your Boat, twice.

• In a circular motion, scrub all surfaces, the backs of your hands, wrists, between your fingers, and under your fingernails. Begin by using one palm on the top of the opposite hand.

• Rub each part of your hands for at least 20 seconds.

• Rinse thoroughly, spending more time than you would ordinarily.

• Dry hands with a clean or disposable towel. The towel is absolutely necessary. This is because the washing separates the microbes and dirt from the skin but does not completely flush them from the skin. The towel removes water along with the suspended contaminants. Air dryers do not do nearly as good a job as old-fashioned towels or paper.

• Use a dry paper towel to turn off the water and use it to open the door to leave the stall, restroom, and outer vestibules.

A hand-washing video can be accessed at either YouTube[15] or the Wall Street Journal[16]. An interactive instructional program[17] is also available.

This video shows kids how to properly wash their hands, one of the most important steps we can take to avoid getting sick and spreading germs to others.

Video at YouTube

Alcohol-based sanitizers

These are excellent alternatives to soap and water, provided that your hands are not visibly dirty, and grime or grease is not layered on your skin. Beware of “waterless” sanitizers that do not contain alcohol. • Apply about ½ tsp (2.5 g) of the sanitizer to the palm of your hand (foam or other)

• Rub your hands, including all surfaces—top, bottom, or between fingers, until they are dry

• If hands are visibly dirty, wash with soap and water first, then use the alcohol-based sanitizer for best results.

Enough hand antiseptic or alcohol rub must be used to thoroughly wet and cover both hands. The front and back of both hands and between and the ends of all fingers are rubbed for approximately 30 seconds until the liquid, foam or gel is dry. The use of a hand antiseptic or alcohol rub is much quicker and more effective than hand washing with soap and water. For picnics, travel, and outings, antibacterial towelettes are convenient possibilities. Organic lavender or lemon essential oils are naturally cleansing, soothing and refreshing plant alternatives, though not equivalent.

There is concern about potential childhood intoxication from alcohol in hand sanitizers. The Maryland Poison Center estimates a two year old weighting 30 pounds might need medical attention after consuming 4 tsp, about 20ml or 8 pumps of a hand sanitizer. Caution is especially advised if hand sanitizers that operate with squirts are used around children.

In addition, the Environmental Working Group’s Skin Deep Cosmetic Safety Database has scored one brand, Purell, 7 out of 10 score for toxicity—ten with the highest hazard, because their ingredients are linked to neurotoxicity, reproductive and developmental toxicity, allergies, endocrine disruption, general toxicity and skin/eye/lung irritation.

Electric dryers

As mentioned, drying with a towel is an important part of hand washing. Electric hand dryers found in many washrooms are not as effective as old-fashioned towels.

In 2008, a study by the University of Westminster[18], London, compared the levels of hygiene offered by paper towels, warm air hand dryers and the more modern jet-air hand dryers. They found that after washing and drying hands with the warm air dryer, the total number of bacteria was found to increase on the finger pads by 194%, and on the palms by 254%. Furthermore, after washing and drying hands with a paper towel, the total number of bacteria was reduced on average on the finger pads by up to 76% and on the palms by up to 77%. These data were confirmed in a 2009 update[20].

In 2005, in a study conducted by TUV Produkt und Umwelt[20], different hand drying methods were evaluated. The bacterial count using paper towels decreased by 24%, but the hot air drier increased the bacterial counts by 117%.

Scientists have also carried out tests to establish whether there was the potential for cross contamination of other washroom users and the washroom environment as a result of each type of drying method. They found that:

• the jet air dryer, which blows air out of the unit at speeds up to 400 mph, could blow micro-organisms from your hands and the unit to contaminate other people and objects in the washroom up to 2 meters (6 feet) away

• use of a warm air hand dryer spread micro-organisms up to 0.25 meters from the dryer

• paper towels showed no significant spread of micro-organisms.

Finally, few people using drying machines actually leave their hands under the blower until they are dry. More often, they grow impatient and finish drying by wiping their hands on their clothes.

Which is best for the flu?

For seasonal or “regular” influenza, a study in Clinical Infectious Diseases, Feb 1, 2009[21], showed that ordinary soap and water is slightly better than alcohol-based rubs. The AMANews, a weekly newsletter sent to physicians by the American Medical Association, also agreed. Of twenty health care workers purposely contaminated with influenza virus, 14 still had live virus on their hands after air drying. Soap and water got rid of the virus, just a tad better than different alcohol-based rubs. Practically, it is not important which you do, just do either one consistently and well. In public health settings[22], the alcohol method is being emphasized, only because it is much more practical in hospitals and clinics for a number of reasons. About 30 seconds of hand washing with soap and water lowers bacterial count of health care workers 58%. For alcohol-based hand rubs, it is 83%.

Excessive use of washing, either soap-water or alcohol-based, is not good either. Normal flora, germs that are supposed to be there, as well as the skin’s own oils and fats, are part of our own defenses against infections. Soap, which is quite alkaline, removes the protective fat secreted by sweat glands, sebum, and fats from the skin, may cause dryness[23]. Therefore overuse of soap, can leave skin irritated, vulnerable, cause minor abrasions and cracks that may actually lead to infections.

Recently,researchers at the School of Public Health in Berkeley[24] observed people for a period of three hours while performing office work in isolation. The subjects touched their eyes, nostrils, and lips an average of 47 times during that time. Their model suggests that hand contact with these target facial membranes is an important means of infection and should be avoided. Risk analysis[25] confirms that 31% of infections with influenza are a result of virus contaminated hand contact with facial membranes. Since virus transmission occurs not only through hand contact, but also through droplets and inhalation, hand washing, although a powerful tool, cannot eliminate viruses spread through those pathways.

The influenza virus also survives well in nasal mucosa, the moist lining of the nasal passages[26]. Shielding or covering a sneeze is another effective hygiene measure, since a large amount of virus is spread during sneezing.

Take-home messages:

• Swine flu viruses can survive on doorknobs and surfaces for 2-8 hours

• A major way you become infected is by seeding germs from your hands to your mouth, nose, and eyes

• 30-40% of virus transmission takes places in households, 20% in schools

• Since the virus is not absorbed from your outer skin, it can be washed away, wash your hands frequently

• Stay at least 6 feet away from people who are sneezing or coughing–the further the better. Shield yourself from the droplet cloud as part of cough etiquette (27).

Related Videos

In this video from the CDC, learn how to help stop the spread of infection and stay healthy. It's easy when you 'Put Your Hands Together'.

Video at YouTube


1. http://www.cdc.gov/cleanhands/

2. http://www.cdc.gov/Features/HandWashing/

3. Kac G, Buu-Hoï A, Hérisson E, Biancardini P, Debure C. Methicillin-resistant Staphylococcus aureus. Nosocomial acquisition and carrier state in a wound care center. Arch Dermatol. 2000 Jun;136(6):735-9. Abstract

4. http://www.newsweek.com/id/215435 Accessed October 27, 2009.

5. http://www.cnn.com/2009/HEALTH/09/24/hand.washing.helpful/index.html Accessed October 27, 2009 6. http://www.cdc.gov/H1N1flu/qa.htm Accessed October 27, 2009.

7. Luby SP, Agboatwalla M, Feikin DR, et al. Effect of handwashing on child health: a randomised controlled trial. 2005 Jul 16-22;366(9481):225-33. Abstract

8.Margaret A. K. Ryan, Rebecca S Christian, Julie Wohlrabe Handwashing and respiratory illness among young adults in military training. American Journal of Preventive Medicine.August 2001; 21(2): 79-83. http://www.ajpm-online.net/article/S0749-3797(01)00323-3/abstract

9. Jefferson T, Del Mar C, Dooley L, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review. British Medical Journal. 11/22/2009;339:b3675. doi:10.1136/bmj.b3675.

10. http://www.asm.org/index.php?option=com_content&view=article&id=38075&Itemid=417 Accessed October 27, 2009.

11. 47th International Conference on Antimicrobial Agents and Chemotherapy, Chicago, Sept. 17-20, 2007. Brian Sansoni, vice president of communication, Soap and Detergent Association.

12. Allison E. Aiello, Elaine L. Larson, Stuart B. Levy. Consumer Antibacterial Soaps: Effective or Just Risky? Clinical Infectious Diseases Aug 2007; 45:662-e76. http://www.journals.uchicago.edu/doi/abs/10.1086/519255

13. http://www.usatoday.com/news/health/2005-10-19-antiseptic-soaps_x.htm.Accessed October 27, 2009.

14. http://www.fda.gov/NewsEvents/Speeches/ucm054018.htm Accessed October 27, 2009.

15. You Tube. Handwashing Video. http://www.youtube.com/watch?v=rrNJt73BG_8. Accessed October 26,2009.

16. Beck, Melinda. Put Up Your Dukes: Fighting Disease With Soap and Water. The Wall Street Journal Health Journal, 2009, pD1. http://online.wsj.com/article/SB124208945194709049.html.

17. CDC. Hand Hygeine. http://www.cdc.gov/handhygiene/training/interactiveEducation. Accessed October 26, 2009.

18. A comparative study of three different hand drying methods: paper towel, warm air dryer, jet air dryer by Keith Redway and Shameem Fawdar of the School of Biosciences, University of Westminster London http://www.europeantissue.com/Files/positionpapers_and_studies/090402-2008%20WUS%20Westminster%20University%20hygiene%20study,%20nov2008.pdf.

19. Position on the use of hot air dryers versus paper hand towels, April 2009. http://www.europeantissue.com/Files/positionpapers_and_studies/090415%20AAA2%20ETS-PP-Warm%20and%20Jet%20Air%20Dryers,%20april2009.doc

20. TÜV Produkt und Umwelt GmbH Report No. 425-452006. A report concerning a study conducted with regard to the different methods used for drying hands; September 2005.http://www.europeantissue.com/Files/positionpapers_and_studies/090410%20T%C3%9CV%20-%20Study%20of%20different%20methods%20used%20for%20drying%20hands%20Sept%202005.pdf

21. Grayson ML, Melvani S, Druce J, Barr IG, Ballard SA, Johnson PDR, Mastorakos T, Birch C. Efficacy of Soap and Water and Alcohol Based Hand Rub Preparations against Live H1N1 Influenza Virus on the Hands of Human Volunteers. Clinical Infectious Diseases. 8/1/2009;48:285–291. DOI: 10.1086/595845.

22. Centers for Disease Control and Prevention.Guideline for Hand Hygiene in Health-Care Settings: Recommendations of the HealthcareInfection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. MMWR 2002;51(No. RR-16):[inclusive page numbers]. http://www.cdc.gov/mmwr/PDF/rr/rr5116.pdf. Accessed October 26, 2009.

23. Boyce JM, Kelliher S, Vallande N Skin irritation and dryness associated with two hand-hygiene regimens: soap-and-water handwashing versus hand antisepsis with an alcoholic hand gel. Infect Control Hosp Epidemiol. 2000 Jul;21(7):442-8. Abstract

24. Nicas M, Best D. A study quantifying the hand-to-face contact rate and its potential application to predicting respiratory tract infection. J Occup Environ Hyg. 2008 Jun;5(6):347-52. 25. Nicas, M, Jones, RM. Relative Contributions of Four Exposure Pathways to Influenza Infection Risk. Risk Analysis. 2009Sept;29(9):1292-1303

26. www.cdc.gov/h1n1flu/guidelines_infection_control.htm Accessed October 27, 2009.

27. Weber TP, Stilianakis NI. Inactivation of influenza A viruses in the environment and modes of transmission: a critical review. J Infect. 2008 Nov;57(5):361-73.

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