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Secondhand smoke in homes: A bigger problem than Singapore authorities think?

How far can cigarette smoke travel between flats? How much secondhand smoke is enough to start affecting your health? Is regulation the only option? The programme Talking Point looks for some answers.

SINGAPORE: He has approached his town council and the Housing and Development Board (HDB). He also tried speaking to his neighbour “on many occasions”.

But “Mr Ng” is at the end of his tether now, with no resolution in sight.

The cause of his problems: Secondhand smoke filtering into his flat from his neighbour’s balcony, “just a metre away”.

“(HDB flats) aren’t that big nowadays … From the living room, (the smoke) quickly gets (into) the entire unit,” said “Mr Ng”, who requested anonymity because his neighbour lives right next door.

“I can’t leave the (balcony doors) open without having to run to the living room to close (them) when we smell smoke and then to air out the house with fans.”

“Mr Ng” keeps his balcony doors closed.

He also installed rubber seals on all the windows and doors, since he has a young child. But even with those precautions, he worries about how much secondhand smoke his 22-month-old daughter might be inhaling.

The agencies he approached have advised his neighbours not to smoke near the balcony and windows, he said, but they “maintain their right” to do so and that “there’s no way they could control where the smoke would end up”.

The number of such complaints about secondhand smoke in homes has risen during the pandemic, to about 150 to 200 each month from 60 to 80 complaints a month in 2018 and 2019.

And immediate neighbours of smokers may not be the only ones concerned. In a look at the extent of the problem, the programme Talking Point found out that the smoke particles can travel across 10 storeys.

This is according to simulations carried out by Zheng Kai, a faculty fellow in architecture and sustainable design at the Singapore University of Technology and Design.

The simulations are based on two blocks 18 storeys high, about 30 metres apart at their widest and located in Buangkok, an estate representative of flats built in the 2000s.

On a still day, “what’s likely to happen is that the smoke particles would just hover around … without settling on the ground”, said Zheng.

“The neighbours in the immediate proximity — maybe just below the smoker, above … and then around him — will most likely be able to smell the smoke.”

But on a windy day, when someone on a lower storey is smoking, the smoke particles may be “carried upwards into a vortex”.

If a smoker is on an upper storey, the same wind would form a vortex that carries and circulates the smoke downwards. “In this case, the neighbours below are all getting the smoke,” said Zheng.

It takes “as short as maybe one minute to a few minutes” for the smoke to dissipate.

The most important factors in determining how far the smoke can travel before that are the buildings’ relative heights and distance between them, as well as the wind direction, he added.

It does not, however, depend on “whether the smoker is smoking in the living room, by the window or on the balcony”.

“No one smokes with their windows closed, and … many households have ceiling fans,” Zheng said. “What that means is that the smoke is dispersed in … small concentrations in all directions.

“All the neighbours in the immediate vicinity would be able to smell the smoke … I’d say perhaps the best solution is to not smoke at all.”


As far as Member of Parliament (Nee Soon GRC) Louis Ng is concerned, the way forward is to bring in government regulation. Twice in Parliament, he pitched a ban on smoking at home near windows and on balconies.

The authorities said in response that it is not possible to use existing laws to impose such a ban and that enforcement might also be challenging. But he thinks otherwise.

“What I raised in Parliament is that actually enforcement is the last tool. Deterrence is the biggest tool,” he told Talking Point.

“If it were illegal to smoke at your windows or balconies and you can see someone there, obviously most people aren’t going to do it, because we’re a country of law-abiding citizens.

“Without regulations, the behaviours usually won’t change; this has been an age-old problem. People have tried all sorts of ways: To talk to the neighbours, to get the authorities — the National Environment Agency, the HDB — involved, even go to court.”

WATCH: How much of your neighbour’s secondhand smoke are you breathing in? (3:49)

For him, legislation and public education go hand in hand, and “it’s not one or the other”.

Last month, he launched a feedback form to which more than 2,100 people have responded. They were “urging for help, not for themselves but really for their children and for family members who have respiratory illness”, he said.

“It’s not a nuisance or smell issue, it’s a health issue. I think the other surprising data is that a majority (74.5 per cent) didn’t speak to their neighbours … They don’t want to strain their relationship, and so they suffer in silence.”

He feels strongly about this issue because of such “constant feedback” he gets during his home visits.

“The Government has to step in to make sure that the voices of these people are heard and our policies address their concerns. And they’re very valid concerns,” he added.

If you want to smoke, you’ll bear the consequences of it. But here we have hundreds dying because of someone else’s decision to smoke, and I don’t think that’s fair.”

About 85 to 90 per cent of the smoke from every cigarette ends up in the air as secondhand smoke — a mixture of what a smoker exhales and what a lit cigarette emits.

Of the 250 known toxic chemicals in tobacco smoke, about 70 can cause cancer. And in Singapore, secondhand smoke is estimated to be responsible for close to 300 deaths annually.

Secondhand smoke contains 250 chemicals known to be harmful — about 70 can cause cancer.

Some studies have shown that the damage to health occurs within five minutes.

“Most of us, when we think of secondhand smoke, we think of lung cancer,” said Yvette van der Eijk from the National University of Singapore’s Saw Swee Hock School of Public Health.

“(But) when it goes into the bloodstream, (secondhand smoke) can cause inflammation in the blood vessels, which can then be a precursor to heart diseases, respiratory inflammation.”

It can also trigger an asthma attack, cot death, ear infections in children, miscarriage and breast cancer.

“There are going to be people who are more sensitive to those inflammatory effects than others,” the assistant professor noted, citing babies and young children.

“At the same time, we also have genetic differences in how we react to certain things. So that’s why … there’s no safe level of secondhand smoke.”

Smoking in homes can affect the health of neighbours, especially young children.


To find out, as an experiment, how much secondhand smoke the Ngs are subjected to, Talking Point brought in air quality expert Seow Wei Jie to measure the PM2.5 readings in their home.

PM2.5, a category of air pollutants with a diameter of 2.5 microns or less, is widely used as a marker for secondhand smoke exposure. Other sources of PM2.5 include vehicle exhaust and cooking fumes.

For two weeks, air quality sensors were left on the balcony as well as in the living room and the master bedroom, where the Ngs’ daughter plays and sleeps respectively.

The balcony readings showed spikes of up to 60 micrograms per cubic metre. By comparison, the World Health Organization (WHO) guideline on safe air is 15 micrograms per cubic metre as a 24-hour average.

While not all the spikes in particulate matter could be attributed to secondhand smoke, some of them matched Mr Ng’s record of when he smelt cigarette smoke.

His indoor air quality, meanwhile, was “acceptable” in general. “Except for some peaks here and there, the levels are mostly well within the WHO’s standard,” reported Seow, an assistant professor at the Saw Swee Hock School of Public Health.

“The living room and the bedroom levels are very comparable … When one goes up, the (level in the) other room also goes up — maybe just delayed by a few seconds because of the diffusion of the air particulates.”

There might be secondhand smoke particles even without the smell, which is a reason air quality sensors are used.

That, however, is with the doors and windows kept shut. She recommended ventilating the flat “once in a while” when the wind is blowing the smoke away from his home.

But he assessed that he “wouldn’t know when the neighbour’s going to smoke and when the wind’s going to change direction”. He said: “I’ll still have to keep my doors and windows closed.”

An air purifier would not do much either. According to the Health Ministry, it is unaware of any air purifier on the market that can completely remove the toxicants from cigarette smoke.

He would consider moving out of his home of six years, although “there are other prevailing factors, like property prices and availability of properties we can move to”, he said.

Van der Eijk thinks “multiple approaches” to the issue could be taken, however, and “not all of them have been tried” beyond treating secondhand smoke in homes “like a neighbourly nuisance”.

WATCH: The full episode Should smoking at home be banned? (21:57)

Likening it to “a ladder of interventions”, the advocate of stronger tobacco control listed education and awareness as the first step.

“Even if there’s something like a public education campaign saying, ‘Oh, actually, when you smoke on your balcony, you’re exposing quite a lot of people’, there are the ones who’d voluntarily go down and smoke outside,” she said.

The next step is to “incentivise smokers” to smoke downstairs, for example at designated smoking points, she cited.

Some estates offer this. Nee Soon South has roughly one smoking point for every three apartment blocks to get smokers out of their flats when they light up. But these are open-air structures, so cigarette smoke does waft out.

Over at Clementi Avenue 4, an enclosed smoking cabin has been on trial since June. It is air-conditioned to draw smokers, and some in the area said they do use it. The smoke also does not affect people outside.

But it is the only smoking cabin of its kind in a residential estate in Singapore and is not cheap: It costs S$19,000 — not including the few hundred dollars a month in operating costs.

Van der Eijk believes the authorities can implement more measures like these before regulating smoking in homes.

“The next level would be we disincentivise it. So that’s like a stick approach; they can still smoke in their homes, but we make it difficult or unpleasant,” she said. “Then the final frontier would be regulation.”

Watch this episode of Talking Point here. The programme airs on Channel 5 every Thursday at 9.30pm.

Source: CNA/dp


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