Qualité de l’air à Singapore

Does Singapore have good air quality?

Singapore experiences varying levels of air pollution throughout the year, and Singapore air pollution has been shown to pose a significant risk to public health. Studies have shown that there is a link between high Pollution Standards Index (PSI) levels and an increased short-term risk to mortality.¹ As a city-state, air pollutants primarily come from traffic and industry year-round but there is also a seasonal risk, posed by haze from forest fires in neighbouring island states.² Severe haze events can cause an increase in hospital admissions due to respiratory illnesses but severe haze events are uncommon and all haze events are short term in their nature.² Routine haze events can have a minimal impact on air quality and Singapore’s Ministry of Health advises that residents continue with activities as normal unless the PSI rises above 100.³ Otherwise, Singapore experiences a similar incidence of adverse impacts on public health from air pollution, as many North American and European cities, such as Prague air quality and Berlin air pollution.²

What is the PSI level in Singapore?

The Singapore air quality index is the Pollution Standards Index (PSI) – it is an alternative to the Air Quality Index (AQI) that is used in Singapore. Many other countries now commonly use their own versions of an Air Quality Index as a common metric for air quality but Singapore’s National Environment Agency (NEA) uses a variant PSI, which was devised by the United States Environmental Protection Agency. The PSI used in Singapore gives a score for air pollution based on the density of six pollutants: PM2.5, PM10, carbon monoxide, ozone (O₃), nitrogen dioxide (NO₂), and sulphur dioxide (SO₂). The NEA provide 24-hour PSI readings (with a rolling average for the past 24 hours) to help residents manage their own exposure to air pollution.⁴ The PSI scale ranges from 0 to 300+, from “Good” to “Hazardous”, with a colour coded scale: green, blue, yellow, orange and red. Singapore’s NEA reports that its PSI has ‘has remained in the ‘Good’ and 'Moderate' range for much of 2019’.⁵

How bad is Singapore pollution?

In 2019, Singapore’s average PM2.5 concentration was 19 µg/m^³, which exceeds the World Health Organisation’s recommended PM2.5 target of 10 µg/m^³ almost twofold giving them a rating in the US Air Quality Index system of ‘Moderate’. The ‘Moderate’ rating indicates that sensitive individuals should avoid outdoor activity, as they may experience respiratory symptoms.⁶ Singapore ranked as having the 52nd worst air pollution levels of the 98 countries with available data based on PM2.5 levels, and 44th worst of the 85 capital cities included. Among global capital cities in 2019, Singapore ranked as more polluted than Taipei (13.9 µg/m^³) and Manila (12.1 µg/m^³), but with cleaner air than Kuala Lumpur air quality (21.6 µg/m^³) and Bangkok air pollution (22.8 µg/m^³).⁶ However, in the region of Southeast Asia, Singapore performed relatively well, achieving the second best air quality status in the region behind the Philippines. In 2019, Singapore AQI ranged between ‘Good’ and ‘Moderate’ for the entire year.⁵ Singapore air quality varies throughout the city and IQAir’s Singapore air quality map can be used to see where pollution is worst, at the top of this page.

Why is it hazy in Singapore?

As a city-state and island, Singapore’s main sources of air pollution are from motor vehicles and industry. However, this is not the source of the infamous and intermittent haze that has at times engulfed the island, making international headlines.

The island of Singapore is surrounded by other island states, including Malaysia and Indonesia, which have large areas of rainforest. In Indonesia in particular, large areas of the forest are often cleared for agriculture, usually by using slash-and-burn practices. Vast swathes of rainforest can be cleared in this fashion – the World Bank reported that 2.6 million hectares of Indonesian forest had been cleared – an area 4.5 times the size of Bali.⁷ This can create huge volumes of toxic smoke, which not only affects Malaysia air pollution and Indonesia air quality, but can be blown to Singapore by southerly winds. Transboundary smoke has caused a haze of varying severities in Singapore in 1997, 2013, 2015 and 2019. In 2015, Singapore’s air pollution was pushed to hazardous levels from transboundary smoke.

The 2015 haze reportedly cost Singapore $1.83 billion (USD) (an average of $468 per resident) from costs incurred from: millions of residents having to stay at home, disruption to air and sea transportation and public health costs for respiratory, eye and skin conditions.⁸ The 2015 haze was particularly severe because the weather phenomenon, El Nino, exacerbated the effects of Indonesia’s dry season, further fuelling forest fires.¹⁰

Poor visibility in Singapore is not always due to transboundary smoke and can often be due to high volumes of water vapour in the air.⁹ Poor visibility therefore does not always correspond with bad air quality in Singapore.

What is Singapore doing about air pollution?

In 2017 Singapore adopted more stringent measures on petrol vehicle emissions by adopting the Euro VI standards, set by the European Union (previously they had only adhered to Euro IV standards).¹¹ This measure aimed to reduce emissions of PM2.5, nitrous dioxide and sulphur dioxide. Further efforts to reduce sulphur dioxide emissions were also taken by Singapore’s National Environment Agency (NEA), who approved the supply of near sulphur-free diesel (NSFD) in 2013 and cleaner petrol from 2017.⁵ Singapore’s Source Emission Test Scheme requires industry to monitor their own air emissions to ensure they are complying with prescribed standards.⁵

A haze of the magnitude of 2015 has not yet repeated itself. Indonesia’s politicians attribute this to forestry and peatland management plans being implemented successfully, following the severe haze of 2015.¹⁰

Singapore’s NEA monitor air pollution closely and comprehensively. They provide residents with a 24-hour PSI reading and a 1-hour PM2.5 reading.¹² These readings act like a Singapore air quality forecast, which allows residents to make informed decisions about their activities and manage their exposure to air pollutants.

Singapore has also introduced “no smoking zones” in busy public areas, such as the busy shopping district on Orchard Road.¹³ Smoking is restricted to designated smoking areas in an effort to reduce adverse health impacts from second-hand smoke. However, critics say that second-hand smoke is a much lesser threat than air pollution from industry and traffic and that the no smoking zones will have minimal impact.¹³

+ Article resources

[1] Andrew Fu Wah Ho. “The Relationship Between Air Pollution and All-Cause Mortality in Singapore”. Atmosphere, 2019.
[2] Erik Velasco and Matthias Roth. “Review of Singapore's air quality and greenhouse gas emissions: Current situation and opportunities”. Journal of the Air & Waste Management Association, 2012.
[3] Ministry of Health Singapore. Impact of Haze on health. Health Hub, November 22, 2019.
[4] The World Air Quality Project. “Singapore PSI and PM2.5 AQI: Why is there a difference between the two readings?”. The World Air Quality Project, June 25, 2013.
[5] National Environment Agency. “Air Pollution”. National Environment Agency, 2020.
[6] IQAir. “2019 World Air Quality Report”. IQAir website, March 18, 2020.
[7] The World Bank. “Indonesia's Fire and Haze Crisis”. The World Bank website, November 25, 2015.
[8] Euston Quah and Chia Wai Mun. “What the 2015 haze cost Singapore: $1.83 billion”. The Strait Times, September 17, 2019.
[9] Audrey Tan. “Visibility is not the best indicator of air quality: NEA”. The Strait Times, January 20, 2016.
[10] Audrey Tan and Luke Anthony Tan. “2018 won't see repeat of 2015 haze crisis: Indonesian Minister”. The Strait Times, May 18, 2016.
[11] Angela Tan. “Singapore to adopt Euro VI emission standards from Sept 1, 2017”. Business Times, December 1, 2014.
[12] Audrey Tan. “askST: Why are Singapore's PSI readings so different from those used elsewhere, and which are correct?”. The Strait Times, November 4, 2019.
[13] John Bryson. “Singapore is trying to tackle its pollution problem with a ‘smoking ban’ – but it won’t work”. The Independent, January 1, 2019.