When you do the dishes and have a little residue of cheese attached to your fork that contrains you to pass a second time your sponge/dishwashing liquid to be perfectly clean.
If we applied this logic to microscopic things on our hands, that would mean that it’s better to clean them twice “just to be sure”. Since it’s impossible to know if we have particularly resistants microbes or something like that, one more soap/rince seems worth
Is this manner of thinking sounds accurate in a scientific way ?
In: Chemistry
> Is this manner of thinking sounds accurate in a scientific way ?
it *can* be, but it depends on the particulars.
in the case of the dishes, the amount of material you can remove in a single scrubbing action is limited, so you have to break away the material layer by layer. in principle, you could have just scrubbed more the first time and gotten all of the material off.
for most instances of hand-washing, this sort of mechanical limitation isn’t a concern. the soap and water solution on your hands can mechanically reach all parts of your hand, and it will remove or destroy 99.9% of contaminants.
> if I wash hands twice, are they significantly cleaner ?
if you wash your hands twice, you’ll have removed 99.9999% of contaminants in total. technically you did *something* but is that “significant”? no.
this relationship of probabilities, percentages, and number of trials is part of statistics and *does* significantly impact many things. medicine in particular. when you get tested for something, like covid or strep, it’s very normal for them to run multiple trials to decrease the likelihood of faulty results.
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