The level of hygiene in Singapore is the best of any Asian country.

Smoking is illegal in the following air conditioned areas with a potential hefty fine:

Shopping Centres
Restaurants
Cinemas
Buses
MRT (Mass Rapid Transport Train)
Taxis
Lifts

It was also illegal to buy and sell Chewing Gum for 10 years from 1993. However since the formed Free Trade Agreement with the United States in 2003, you can now buy two types of chewing gum. One is a sugarless gum for a breath freshener and the other is a teeth whitening gum.