To prevent the spread of germs including coronavirus, health experts suggest that we should often wash our hands. But why is it important to scrub our hands for at least 20 seconds.
Hand hygiene can protect against respiratory and diarrheal infections. With the coronavirus (COVID-19) outbreaks, this has become more important than ever. Frequent handwashing is one of the best measures to prevent Covid-19 infection, which mainly spreads through respiratory droplets released when an infected person coughs, sneezes, breathes, sings or talks. This is because you can contract the deadly virus if you touch your eyes, nose, and mouth with your unwashed hands that may have touched a contaminated surface or objects.
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Therefore, premiere health agencies including the World Health organisation (WHO), the US Centers for Disease Control and Prevention (CDC) as well as the Ministry of Health and Family Welfare recommend that we should often wash our hands with soap and water for at least 20 seconds or use a hand sanitizer with at least 60% alcohol to prevent the spread of the novel coronavirus. Now, the question is why we should scrub our hands for at least 20 seconds?
Researchers from Hammond Consulting Limited have explained the physics behind it in an article published in Physics of Fluids, a peer-reviewed monthly scientific journal published by the American Institute of Physics. Using a simple model, they have described the key mechanics of handwashing, estimating the time scales on which particles, like viruses and bacteria, were removed from hands.
The physics behind handwashing explained
Particles are trapped on the rough surfaces of the hand in potential wells, and so the energy from the water flow must be high enough to get rid of them. That is, a stronger flow removes particles more easily, and the strength of the flowing liquid depends on the speed of the moving hands the researchers stated.
“If you move your hands too gently, too slowly, relative to one another, the forces created by the flowing fluid are not big enough to overcome the force holding the particle down,” Science Daily quoted author Paul Hammond as saying.
Hammond’s model also showed that it takes about 20 seconds of vigorous movement to dislodge potential viruses and bacteria. The researchers believe that understanding the mechanisms that physically remove particles from hands may help in formulating more effective, environmentally friendly soaps.
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When you must wash your hands
The CDC has developed a list of key times to wash hands. It includes:
- Before, during, and after preparing food.
- Before and after eating food.
- Before and after caring for someone at home who is sick with vomiting or diarrhea.
- Before and after treating a cut or wound.
- After using the toilet.
- After changing diapers or cleaning up a child who has used the toilet.
- After blowing your nose, coughing, or sneezing.
- After touching an animal, animal feed, or animal waste.
- After handling pet food or pet treats.
- After touching garbage.
To prevent the spread of COVID-19 virus, the health agency suggests that you should also wash your hands before and after
- Touching your eyes, nose, or mouth.
- Touching your mask.
- Entering and leaving a public place.
- Touching an item or surface that may be frequently touched by other people, such as door handles, tables, gas pumps, shopping carts, or electronic cashier registers/screens.
Although washing hands with soap and water is the best way to get rid of germs, you can use an alcohol-based hand sanitizer that contains at least 60% alcohol in situations where soap and water are not readily available.
This post first appeared on The Health Site
