Science – The science hand washing

It is clear that the Covid-19 pandemic currently sweeping the world will be an event comparable to the great Spanish Flu pandemic of 1918. To compound the situation, Covid-19 is much more contagious than influenza. The Government has recommended social isolation and simple hygienic measures to slow down the spread of Covid-19. Coughing and sneezing into your hands will create a film of virus and mucus, which is likely to be transmitted to others via handshakes and hugs. Hand washing represents the single most simple and effective precaution for most people.

There is a great complexity of micro-organisms that normally exist on human skin. These include numerous types of bacteria, fungi and sweat organisms which, together with conventional grime, are likely to act as host for incoming coronavirus organisms. Viruses and bacteria are very different in many ways. Bacteria cause food poisoning, gastritis, pneumonia and so forth. Viruses are much smaller than bacteria and generally cause many serious health problems such as Covid-19, flu or AIDS. Research has revealed that viruses and bacteria often act in cooperation, so removing bacteria by washing your hands is also likely to eliminate co-existing viruses such as coronavirus. Medical practice confirms that washing your hands thoroughly with soap for 20 seconds will substantially reduce both the levels of grime, sweat and the associated bacteria and viruses. Soap or detergents in water form microscopic bubbles (called micelles), which can wash away these contaminant films of skin organisms, including Covid-19. Regular, thorough, 20-second hand washing is critical to achieve and maintain a really clean hand-skin surface.

There are situations where soap and water washing are inconvenient and in such cases hand sanitisers are a second-best option. Hand hygiene before eating a takeaway meal is one such situation. Common hand sanitisers are likely to include one of the following components: ethyl alcohol or isopropanol. The alcohol is usually mixed 2:1 with aloe vera gel to reduce superficial damage to the skin. The same duration of washing – 20 seconds – is needed when using sanitisers as for soap and water. These sanitisers are normally available as commercial products but may be difficult to source in the current crisis because of high demand. If so, the alcohol components and the aloe vera are likely to be separately available and a home-made sanitiser (two parts alcohol to one part aloe vera gel) should work just as well as the commercial products. One caution about hand sanitiser solutions: ethyl alcohol especially, and isopropanol to a lesser extent, are volatile. Once the alcohol in the sanitiser has evaporated the clean hygienic state of your hands will decline again. Therefore, it is necessary to repeat the sanitising process regularly to maintain hand hygiene. If your need for hand hygiene is urgent and neither soap nor sanitiser is available, then consider using a high-alcohol spirit – such as vodka – as a sanitiser.