Washing our hands with soap and water is one of the easiest and most effective ways of keeping ourselves clean and protecting ourselves against different viruses and bacteria.

How viruses and bacteria spread

One of the main ways bacteria and viruses spread is through our hands. Think of all the different things, surfaces and people that we touch on a daily basis. By doing so we are spreading our own germs as well as picking up germs from other people. It’s no wonder that our hands are carrying on each moment an average of 3200 different bacteria from more than 150 different species (1).

Our skin has a naturally oily and organic structure. As such, it is an excellent environment for bacteria and viruses to grab on to and to thrive in. From hands, the bacteria and viruses spread easily on to the face and from there into the body. According to some research, we’re touching our faces about 23 times in an hour, which makes at least once every two to five minutes (2). Each time we do so, we’re spreading the germs on our hands on to our faces. Particularly vulnerable are the mouth, nose and eyes from where the germs have an easy entry into the organism.

How soap and handwashing help to protect us

Washing hands with soap and water is one of the easiest and most effective ways of keeping our hands clean and protecting ourselves against different germs. Soap molecules have a special structure, which allows them to connect with both insoluble (dirt, oil, grease) and soluble elements (water) at the same time, making the insoluble particles soluble and easily removable with water. Not only does soap physically remove dirt and germs, it can also destroy some of the bacteria and viruses. (You can read more about how soap works here).

Washing with water only is not as effective. Our hands emit natural oils and grease, which gets easily mixed with dirt on our hands. As we well know, oils and grease do not mix with water. In addition, dirt itself is often insoluble. Soap helps to dissolve the grease and make it more easily removable. That’s why we cannot get our hands completely clean when using just water.

Relying on hand sanitizer is not as effective either. First of all, simple alcohol-based sanitizers can’t kill all viruses and bacteria (like norovirus, Giardia, and C. difficile for example). Secondly, sanitizers only kill viruses and bacteria, but don’t remove them. Whereas soap and water both kill and remove germs by washing them away alongside with other dirt and chemicals you might have on your hands. Also, sanitizers may not be as effective when hands are visibly dirty or greasy. The friction of lathering and washing away the organisms makes handwashing more effective.

Does it matter weather to use solid or liquid soap? The short answer is no. Soap works mainly because of the cleaning agent (the surfactant) in its composition. There are some differences in the surfactants used in solid versus liquid soaps, but it does not make that big a difference when it comes to the ability of cleaning hands. Though, solid soap bars may have a slight advantage – rubbing hands physically against the soap bar may help the wash to last longer and be more thorough.

As important as washing your hands is washing them in a correct way. For washing to be effective, it’s recommended to wash hands at least for 20 seconds, covering all different parts of the hand from palms to fingers and fingernails.

Washing your hands regularly with soap and water can literally save your life!

(1) Frier, N. et al. The influence of sex, handedness, and washing on the diversity of hand surface bacteria. Proceedings of the National Academy of Sciences Nov 2008, 105 (46) 17994-17999; https://www.pnas.org/content/105/46/17994

(2) Kwok, Y. et al. Face touching: A frequent habit that has implications for hand hygiene. American Journal of Infection Control, Volume 43, Issue 2, 112 – 114; https://www.ajicjournal.org/article/S0196-6553(14)01281-4/fulltext