Your hands collect dirt and germs throughout the day. As you shake hands and touch your face, your hands become a perfect way to spread germs and infections.
Washing your hands prevents this, but you have to do it the right way.
Given how important it is to our health, scientists have dedicated extensive studies to determine the benefits of hand washing.
Doctors get trained on hand washing as part of their studies in medical school.
One of the most important parts of good hand hygiene is using soap.
The CDC in fact mentions soap twice in their guide to handwashing:
Wet your hands with clean, running water (warm or cold), turn off the tap, and apply soap. Lather your hands by rubbing them together with the soap. Lather the backs of your hands, between your fingers, and under your nails.
Source: When and how to wash your hands
The CDC used several studies to come to this conclusion. We've summarized the data behind these recommendations below.
In these studies, scientists measure exactly how much of a difference soap makes when washing your hands.
In the first study, researchers had volunteers first touch door handles and railings.
They then asked some of the volunteers to wash their hands with soap, others to wash with just water, and another group to not wash at all.
They found that 44% of those who didn't wash their hands had detectable fecal bacteria on their hands. Yes, door handles and railings are just as gross as your mother said they were.
When volunteers washed their hands with water, only 23% had detectable fecal bacteria.
Those who washed their hands with soap had the best results of all with only 8% showing detectable fecal bacteria.
Source: The Effect of Handwashing With Water or Soap on Bacterial Contamination of Hands
Fecal bacteria isn't just gross, it can also carry diseases. When we get diarrhea or other gastrointestinal disease, it often comes from touching public surfaces and not washing our hands properly afterwards.
Hand Washing & Child Health
In some cases, access to soap can be a matter of life and death.
Infections are some of the greatest dangers to children in the developing world.
Researchers in Pakistan gave soap and education on hand washing to 300 households in Pakistan and compared their health to 306 households that did not receive the intervention.
They wanted to see whether hand washing with soap could potentially save lives.
They found that in households given soap and hand washing advice, kids had half the rate of pneumonia and diarrheal illnesses compared to those that did not receive soap.
Effect of handwashing on child health: a randomised controlled trial
CDC Guide to Handwashing
We've summarized the most important steps to good hand hygiene in the guides below: