Hong Kong already has one of the world’s lowest smoking rates at around 8.5 per cent. The government wants to cut it further.
Offenders are facing on-the-spot fines of $380, with harsher penalties for larger quantities.
Local media reported at least two people were penalised by authorities for using e-cigarettes as the ban took effect.
The rules also apply to tourists visiting the city. Authorities have also been working with tour agencies and airlines to step up promotion ahead of the new smoking controls.
The ban takes effect ahead of mainland China’s Labour Day “golden week” holiday. The city is expecting almost one million mainland Chinese visitors during the five-day holiday period.
A recent survey found that 55% of people who vape intend to continue doing so.
Officials say the bans aim to protect young people from developing a smoking habit.
