Hot water or cold? Solid soap or liquid? Towels or dryers with hot air? This ritual became the most important for many of us – we resort to it several times a day. But how to do it right, you know? Wash your hands – it would seem that it can be easier. Although there is much evidence that washing hands after you've been in the toilet, before eating or after a trip on public transport can reduce the spread of diseases, only 5% of people wash their hands properly.
The study, which was attended by more than 3,000 people, showed that 10% of people leave public toilets without washing their hands, and if they wash, in 33% of cases – without using soap. Unfortunately, we can not resist the temptation to touch our faces, allowing microbes to penetrate from our hands into our noses and mouths, where they can then enter the body. Researchers from Brazil and the US found that we touch surfaces in public places an average of 3.3 times per hour and touch their mouths or noses about 3.6 times per hour.
Obviously, we need to wash our hands properly. The problem is that there are a lot of myths about how to do it.
Do hot water need to clean hands?
69% of people believe that the temperature of water affects the effectiveness of washing hands. It is true that heat can kill bacteria (so we heat some foods thermally before eating them), but the water must be boiling water. Salmonella, for example, can withstand a temperature of 55 degrees for more than 10 minutes. If you put your hands in such water, you would get serious burns in 30 seconds.
To find out exactly how many microbes remain on the hands after washing in water at a temperature of 4.4 to 50 degrees, scientists from Florida used the glove method with juice. However, it is unlikely that you would like to taste this juice. The volunteers' hands were rubbed with bacterial broth or raw minced meat. Then they were washed in water at a certain temperature. Then they were put on latex gloves and poured a special solution into them. After a minute hand massage through the glove to make sure that all the bacteria got into the liquid, the glove juice was collected with a pipette and tested in a laboratory. It turned out that, regardless of whether there was water of cold, hot or medium temperature, there was no statistically significant difference in the number of bacteria that remained in the hands of people.
But before you start saving hot water, do not forget the vagaries of human behavior. During the experiments, washing hands was clearly indicated by time, but in real life, if the water is very hot or very cold, we try not to wash our hands for a long time. Relatively speaking, pleasant warm water can induce you to linger at the wash basin.
Which is better: antibacterial solution or soap?
A lot of research has been done on this topic. Back in 2007, scientists came to the conclusion that a substance that is usually added to an antibacterial hand washing solution – triclosan – does not reduce the number of bacteria that remains in the hands of people. In any case, not more than usual soap, and certainly does not prevent the spread of infections. The study from 2015 came to the same conclusions. Meanwhile, laboratories have also shown that triclosan can increase the risk of antibacterial resistance and changes the hormonal background in animals, which led to its prohibition in the US and EU countries.
So back to soap and water.
Do I need to dry my hands after washing?
When you are in a hurry, you let the water from your hands just drain, shaking them. This is normal if you do not touch anything when you exit the bathroom. If you touch things, you can pick up germs, because they are easier to transfer to wet hands.
You also miss the benefits of drying hands, because it alone can reduce the level of remaining microbes in your hands.
Drying hands with air or a towel?
There is much debate on this subject. Most publications are limited to the use of disposable paper towels. First, it's faster than waiting for a traditional electric hand dryer to do its job. In a study in New Zealand, it was found that people need to wait about 45 seconds while the dryer evaporates excess moisture on their hands. Most of us do not like to hang out that long.
Now, of course, there is a new generation of inkjet dryers that work faster. They showed that you can dry your hands quickly and efficiently, just like a paper towel. Ten seconds with a towel or jet dryer leave the hands equally dry.
But jet dryers have been criticized: they have become so powerful that they can spread germs around the room. A study at Westminster University found that the most powerful hand dryers could spread the virus to a distance of up to 1.5 meters across the room, and a later study increased it to three meters. But these studies are not reliable 100%, because they were sponsored by manufacturers of paper towels. It is necessary to conduct more research in public toilets, rather than in laboratories.
Another study conducted in the US showed that if the toilets were clean and well-groomed, people are more likely to wash their hands. If the shells are dirty, people rush to leave the latrine.
Whichever method of hand washing you choose, the main conclusion that can be drawn from these studies: wash and dry hands longer than used. To work well with foam, with the palms and the back of the hands, and also to clean the skin between the fingers, under the fingernails and wrists, it takes at least 15-30 seconds.
However, all materials in this article are for general information only and should not be considered a substitute for the medical prescriptions of your own doctor or other medical professional. Always consult your doctor if you are concerned about your health.