Study after study shows marked reductions in transmission in public spaces when hand hygiene is practiced, and a recent study found nearly undetectable influenza particle levels after hands contaminated with influenza were washed with either soap and water or an over-the-counter gel containing at least 50 percent alcohol.

CNN: Commentary: Flu and your health on a plane

But it all started when Singapore's migrants took up hawking in the 1950s and 1960s, and the government became concerned about hygiene, the former Public Health Commissioner Daniel Wang tells the BBC's Helier Cheung.

BBC: Why are there hawker centres in Singapore?

In the early days, for example, soap salespeople helped educate the public about germs and the importance of hygiene.

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