2023-04-07 09:36:48
This article is republished from The Conversation under a Creative Commons license. Read the original article.
It was published in the Junior section for children
Every day during our different activities, we touch many different surfaces with our hands that other people have touched (in public transport for example), someone else’s hand or even a handkerchief for example.
On these surfaces, there is dirt (dust, grease, stains, etc.), but also microorganisms commonly called microbes. These are small microscopic organisms (invisible to the naked eye), such as bacteria and viruses, which can make us sick (like the famous virus that causes Covid).
So when our hands are in contact with the surfaces, dirt and microbes will settle there, and if we then touch our face, for example, the microbes can enter our body and infect it.
Soap and gel are not used for the same thing
You can wash your hands with soap and water. Soap molecules have one end that sticks to water and the other end that sticks to grease from dirt: soap acts as a bridge between water and dirt.
By rubbing your hands, the soap removes the dirt from the surfaces and the soap molecules that have caught the dirt leave with the rinsing water, our hands are clean. Soap can also act on microbes: they are surrounded by an envelope (also called a wall in bacteria) which is there to protect them. As this envelope is also made up of fat (like dirt), the soap will cling to the envelope that surrounds the microbe, detaching it from the surfaces and leaving everything with the rinsing water. This attachment can also damage this envelope and certain microbes, such as viruses, will not be able to survive with a damaged envelope.
For its part, the hydroalcoholic gel disinfects the hands, that is to say it kills microbes, but it does not wash the hands and does not take off the dirt which would then be eliminated by rinsing, as a soap.
If the hands are dirty, do not use gel because it does not remove the dirt and it will also be less effective, the dirt will “hide” the microbes by forming a barrier around them.
Alcohol to get rid of germs
Soap is already very useful and should therefore be used first. But when we are outside it is not possible to use soap and water. In these cases, we can use hydroalcoholic gel.
This gel is a mixture mainly of water and chemical compounds called alcohols (easy to recognize, they have “-ol” names like ethanol or isopropanol). When you rub your hands with the gel, the alcohol molecules will stick to the microbes.
We have already seen that the envelope of microbes is made up of fat, but there are also other compounds called proteins. The alcohol molecules will modify the structure of the envelopes of the microbes by damaging these proteins, that is to say that the proteins will disorganize and allow the alcohol molecules to pass inside the microbes. The microbes will then be completely destroyed.
How to properly use hydroalcoholic gel
For it to be effective, the gel must contain at least 65% alcohol (to be checked on the label), you must put the equivalent of a large hazelnut in the palm of your hands (which must be visibly clean ) and rub the fingers, palms and back of the hands well until the beginning of the wrists for 30 seconds, the hands must be dry at the end.
The hydroalcoholic gel remains a chemical product that should not be used all the time, because it will damage the skin, moreover the plastic container can pollute the environment.
Finally, the gel does not like heat so avoid leaving the bottle in the bottom of a pocket or in direct sunlight, the alcohol compounds will evaporate and the gel will be less effective.
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