- Following the outbreak of COVID-19 in several countries, various measures have been suggested to reduce the risk of infection. Cleaning one’s hands with an alcohol-based hand rub or washing them with soap and water is essential, as specified by WHO.
- The grime on our hands contain innumerable viruses and bacteria. Washing hands without soap helps reduce the amount of microbes but does not remove most of the virus and bacteria completely. Therefore, using soap becomes far more effective in removing microbes.
- Viruses such as coronavirus, influenza-causing viruses, Ebola, Zika have their genetic material encased in a layer of fat called the lipid envelop.
- Soap molecules are pin-shaped with a head that is waterloving (hydrophilic) and a tail that is oil-loving (oleophilic). Being oleophilic, the tail portion of the molecule tends to have an affinity for and ‘competes’ with the lipids in the virus envelope.
- Since the chemical bonds holding the virus together are not very strong, the long oleophilic tail gets inserted into the envelope and tends to have a ‘crowbar’ effect that breaks the lipid envelope of the virus.
- The tail also competes with the bond that binds the RNA and the lipid envelop thus dissolving the virus into its components which are then removed by water.
- In order to be effective, sanitisers should contain at least 60% alcohol. Unlike soap lather, the alcohol does not come in contact with all parts of the hand. Sufficient use of sanitiser on the hand can increase the coverage.
- Soaps produce better results when hands are visibly dirty or greasy, unlike sanitisers.
- Unlike water, alcohol run does not remove the dead viruses from the hand. While a sanitiser can quickly reduce the number of microbes, it does not get rid of all types of germs, and is “not as effective when hands are visibly dirty or greasy”.
But why 20 seconds?
- Hands are rougher surfaces than, say, metal or glass, meaning that we need to work a little harder to ensure that soap suds can latch onto any viral particles, dissolve their envelopes, and inactivate them. “It gives you time to get into the webs of your fingers and the backs of your hands
What is soap?
- Soap, is common phrase for what chemists call “amphiphiles.” These are molecules that have a dual nature.
- Then the harmless shards of virus get flushed down the drain. And even if it the soap doesn’t destroy every virus, you’ll still rid them from your hands with soap and water, as well as any grease or dirt they may be clinging to. Soap will also wash away bacteria and other viruses that may be a bit tougher than coronavirus, and harder to disintegrate.