I read that somewhere (couple weeks before the first reports from Wuhan actually, a toilet in our office building in Germany had it on a poster) but I don't know why this works. Why isn't it sufficient to rub over every part (between fingers, back of your hand, etc.)? Soap isn't anti-viral, what does longer exposure do? Am I supposed to just rub over every part of my hand N times until 20-30s have passed or does it just need to sit there for the time?
The soap also takes time to work. Soap binds to or encapsulates nonpolar molecules in a polar envelope, allowing nonpolar things to be washed away by water. That encapsulation takes a little bit of time.
