A minimum of 20 seconds – this is all it takes to effectively wash off not only dirt, but also bacteria and viruses from your hands. But it is not everything! The way we wash our hands is equally important. This must be done quickly and vigorously.
The latest research shows that if we really want to get rid of bacteria and viruses from our hands, we should wash them for at least 20 seconds. It is also important to do this quite vigorously. Paul Hammond (a Cambridge mathematician and one of the authors of the analysis) created a special mathematical model, through which he showed how the hand washing process looks like from the point of view of physics.
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How to wash your hands properly? Vigorously
Paul Hammond presented the conclusions from his observations in the magazine “Physics of Fluids”. The researcher created a mathematical model of hand washing.
It consists of two wavy surfaces (representing both hands) that move rapidly relative to each other (when washing). Between them there is a thin layer of liquid (water). The surfaces have many unevenness (they represent skin depressions) and it is in them that accumulate, among others, bacteria and viruses.
To get them out of these holes, enough water energy is needed to flush them out. And this, in turn, depends on the speed of the hand’s movement.
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That is why it is so important to wash your hands thoroughly, quickly and vigorously. For ease, Paul Hammond likens it to rubbing a stain off a shirt, i.e. the faster the movement, the easier the dirt can be removed.
“If the hands are moved too gently and slowly, the resulting forces exerted by the fluid are not sufficient to overcome the holding force of the particles,” explains Paul Hammond.
Hand washing. 20 seconds is enough
The mathematician emphasizes that vigorous hand scrubbing does not remove particles quickly. Therefore, adequate time is needed. The model shows that 20 seconds is enough to get rid of bacteria and viruses.
Paul Hammond points out that understanding the physical mechanism by which particles are removed from dirty hands could aid in the development of more effective and environmentally friendly soaps in the future.
Also read:
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