Taking a puff in non-smoking areas without getting caught is about to get harder.

The National Environment Agency (NEA) intends to deploy surveillance cameras with high-definition thermal sensors around the island to help detect smoking in prohibited areas.

Smoking is now prohibited in about 32,000 premises and locations, such as entertainment outlets, shopping malls, office premises, hospitals, bus stops, covered walkways, lift lobbies, stairwells and entrances to buildings.

Other unhygienic acts like spitting and littering will also be captured by these cameras, which are being used for the first time here.

Cameras deployed in areas where smoking is prevalent but prohibited will record images of the person as well as the date and time.

The tamper-proof thermal cameras, which can detect a person holding a lighted cigarette during the day or night, will be placed discreetly on rooftops, in common corridors and staircases of residential buildings, multistorey carparks and other locations.

The thermal cameras will focus only on the common corridors, lift lobbies or staircase landings, areas where smoking is prohibited.

NEA said it will be mindful of the privacy of members of the public.

There are strict protocols governing the viewing of the footage from the cameras and only authorised NEA staff and the vendor may handle and view the video footage for official purposes.

NEA wants the contractor to carry out about 140 camera deployments a year, with 10 to 15 deployments a month in places where the cameras are needed.

It is asking for quotations from contractors now, before deciding on the implementation date.

Cameras are just the latest in a series of government moves to gradually extend the smoking ban to more public places since the 1970s to safeguard non-smokers from harmful second-hand smoke.

In 2013, smoking was banned in common spaces in residential buildings as well as bus stops. The ban was extended to reservoirs and parks in public and private housing estates in 2016.

Last October, smoking was banned in common areas of public universities and other education institutions. It was also banned in private-hire cars and excursion buses.

By the end of this year, smoking will be barred in the No Smoking Zone of the Orchard Road precinct established this year. The delay was to give businesses more time to set up designated smoking areas.

As smoking curbs are extended, the number of offenders has increased. The NEA issued about 22,000 tickets last year to people smoking at prohibited areas, compared with 19,000 in 2016.

People caught smoking in prohibited areas may be fined $200 on the spot, or up to $1,000 if convicted in court. The public can report infringements via the NEA website or MyENV app.