Hand washing is the practice of cleaning the hands with soap and water. People may wash visibly dirty hands to avoid getting dirt, grease, or other substances on things they touch. More importantly, hand washing limits the spread of microscopic germs that can cause infectious disease or food poisoning.
How hand washing prevents disease.
Some viruses or bacteria that cause illness can survive outside the body for hours or days. You can pick up such germs on your hands by touching contaminated surfaces or infected people. Germs may then pass from your hands to your face through touching, entering the body through the eyes, nose, or mouth. Germs can also enter the body through food that you touch. Hand washing kills such germs or removes them from the hands, preventing these routes of infection.
Some uncooked foods contain bacteria or other organisms that can cause food poisoning. Other foods may hold such germs on their surface if they are not properly washed. People who handle uncooked or unwashed food can risk becoming infected if they touch their face. They can also spread germs to food that has already been cooked or washed, re-contaminating it. Washing the hands immediately after handling uncooked or unwashed foods can stop the spread of disease-causing organisms to other foods or surfaces.
How to wash.
To wash your hands, first wet them with warm or cold clean, running water. Apply soap and lather the hands by rubbing them together. Scrub all parts of both hands, including the backs of the hands, the spaces between the fingers, and under the fingernails. The United States Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend scrubbing the hands for 20 seconds, about the time it takes to sing “Happy Birthday” twice. Then, rinse the soap from your hands with clean, running water and dry them with a paper towel or air dryer.
When to wash.
The CDC and WHO recommend that people wash their hands frequently. The CDC recommends washing the hands before, during, and after preparing food; before eating; before and after caring for someone who is vomiting or has diarrhea; before and after treating a wound; after using the toilet; after changing diapers or helping a child that has used the toilet; after blowing the nose, coughing, or sneezing; after touching an animal, animal feed, or animal waste; after handling pet food or pet treats; and after touching garbage.
History.
People have washed their hands for personal hygiene for thousands of years. Ritual washing, called ablution, was thought to cleanse a person of impurity.
The importance of hand washing to reduce the spread of infection was demonstrated in the 1840’s by the Hungarian doctor Ignaz Semmelweis. Through the use of experiments and statistics, Semmelweis found that hand washing among staff delivering babies at the Vienna General Hospital greatly reduced deaths among patients. However, he was unable to convince most members of the medical community.
In the late 1800’s, the germ theory of disease was developed, with significant contributions from the French microbiologist Louis Pasteur and the German bacteriologist Robert Koch. Germ theory is the understanding that tiny living things can enter the body and cause disease. Around this time, the British surgeon Joseph Lister realized that germs could be carried by a surgeon’s hands and instruments. He insisted on the use of antiseptics to kill germs on hands, instruments, and dressings, as well as on the patient. The use of Lister’s techniques virtually eliminated infections resulting from surgery.
At the same time, the cost of consumer goods, including soap, was declining as a result of the Industrial Revolution, a period of swift technological development. In the early 1900’s, soap manufacturers began marketing frequent hand washing and other forms of hygiene as a way of showing wealth and status. Before the Industrial Revolution, only the rich could afford such high levels of cleanliness. Hand washing remains one of the most effective methods to slow the spread of such infectious diseases as the common cold, influenza, and COVID-19.
