Singapore's Air Pollution: Understanding The Root Causes

Air pollution is the leading environmental health risk, causing an estimated 6 to 7 million premature deaths and US$5 trillion in welfare losses annually, according to a UN report. Singapore, a Southeast Asian city-state, has been exposed to the Southeast Asian haze problem, which has been linked to increased morbidity and mortality. While Singapore has implemented measures to improve air quality, it fell short of its 2020 targets for particulate matter and ozone. The causes of air pollution in Singapore are multifaceted, ranging from regional forest fires to ground-level ozone formation, and the country continues to face challenges in meeting its air quality goals.

Haze from forest fires in neighbouring countries

Singapore has not been immune to the impacts of this haze, with the air quality deteriorating to "unhealthy" levels due to the smoke from these fires. The Pollutant Standards Index (PSI), which is used to gauge air quality, has on several occasions entered the unhealthy range during haze periods. The dominant pollutant during these periods is PM2.5, which refers to particulate matter fine enough to enter a person's bloodstream through the lungs. Exposure to elevated levels of PM2.5 can lead to respiratory issues and is considered a serious health risk.

The Singaporean government has taken steps to address the haze problem and mitigate its impact on the country. In 2014, Singapore passed a cross-border air pollution law, making those who cause haze both criminally and civilly liable. Additionally, Singapore has cooperated with Indonesia to combat forest burning, providing satellite data and coordinating responses through the Association of Southeast Asian Nations (ASEAN).

The economic impact of haze from forest fires in the region has been significant. The 1997 haze outbreak, caused primarily by large-scale forest burning in Indonesia, resulted in economic losses of approximately US$60-70 million for Singapore's tourism industry alone. More recently, the 2019 fires across the affected countries resulted in a minimum of US$5.2 billion in damage and economic losses, according to World Bank estimates.

The haze from forest fires in neighbouring countries continues to be a challenge for Singapore, and regional cooperation and mitigation efforts are crucial to reducing its occurrence and impact on the environment and human health.

Weather conditions

One of the primary weather-related challenges Singapore faces regarding air quality is the seasonal haze. During certain periods, particularly in the dry season, neighbouring countries in the Mekong sub-region engage in agricultural burning, releasing massive amounts of smoke into the atmosphere. This smoke, known as the "transboundary haze," drifts into Singapore, leading to a significant deterioration in air quality. The haze is composed of fine particulate matter, primarily PM2.5, which is considered one of the most harmful pollutants to human health. It can penetrate deep into the respiratory system, causing respiratory and cardiovascular issues.

Ozone pollution is another critical weather-influenced air pollution issue in Singapore. Ozone is a secondary pollutant formed when primary pollutants emitted by vehicles, refineries, and chemical plants react chemically in the presence of sunlight. While “good ozone” in the upper atmosphere protects life on Earth from harmful ultraviolet rays, ground-level ozone is a significant component of smog and a health hazard. Weather conditions such as ambient temperature, ultraviolet levels, wind speed, wind direction, and rainfall impact the formation and dispersion of ground-level ozone. For example, in March 2021, northern Singapore experienced unhealthy air quality due to elevated ozone levels, which were attributed to high temperatures and ultraviolet levels.

Additionally, Singapore's geographical location in Southeast Asia makes it vulnerable to the region's environmental changes. Large-scale fires, such as those caused by peat burning in Indonesia, can directly impact Singapore's air quality. These fires release massive amounts of pollutants into the atmosphere, affecting not only the local area but also neighbouring countries.

To address these challenges, the National Environment Agency (NEA) of Singapore conducts emissions inventories and studies to identify key sources of air pollutants and develop effective air quality management strategies. The NEA continuously monitors air quality and takes preventive measures to mitigate the impact of weather-related air pollution on public health.

Industrial emissions

One of the main sources of industrial emissions in Singapore is the burning of fossil fuels by power stations, which releases sulphur dioxide into the atmosphere. In 2019, Singapore exceeded its target for maximum 24-hour mean sulphur dioxide emissions by 7 µg/m3. While the country did meet its annual mean target for these emissions, the 24-hour mean measures the highest 24-hour reading in a year, indicating a spike in emissions during a specific period.

To address industrial emissions, the Singapore government has implemented a range of measures. For example, it has tightened industrial emission standards for new and existing plants from 2015 to 2023. The National Environment Agency (NEA) also plays a crucial role in monitoring air quality and identifying sources of pollution. By conducting emissions inventories and studies, the NEA can develop effective air quality management strategies.

However, Singapore's air quality is also affected by regional factors beyond its direct control. The country often experiences haze pollution due to agricultural fires in neighbouring countries, which can significantly impact air quality and human health in Singapore. This transboundary haze is a complex issue that requires regional cooperation and efforts to address.

Furthermore, weather conditions such as ambient temperature, ultraviolet levels, wind speed, wind direction, and rainfall can influence the formation of ground-level ozone, a harmful pollutant and a primary component of smog. For instance, in March 2021, northern Singapore recorded a temperature of 35.3°C, along with high ultraviolet levels, which contributed to elevated ozone levels that reached an unhealthy range.

Fossil fuel burning power stations

Singapore's air quality has been affected by its reliance on fossil fuels. As of 2015, 95% of the country's electricity is produced using natural gas, with oil contributing 1%. In 2019, the Minister for Trade and Industry, Chan Chun Sing, acknowledged the need to transition to a more sustainable energy model while maintaining a reliable and affordable energy supply.

To address the issue of air pollution from fossil fuel burning power stations, the Singapore government has implemented several measures. In 2019, the Carbon Pricing Act was introduced to reduce carbon emissions by imposing a tax on greenhouse gas emissions. The Energy Market Authority (EMA) also launched the "4 Switches" strategy, which aims to enhance energy efficiency, increase the adoption of renewable energy sources, and integrate advanced technologies such as carbon capture and storage.

In addition, the Singapore Green Plan outlines initiatives to expand green spaces, phase out new registrations of diesel vehicles by 2025, expand the electric vehicle charging infrastructure, and increase the deployment of solar energy. By 2030, Singapore aims to generate 2 gigawatts of electricity through solar power.

The EMA has also initiated plans to build and operate two new hydrogen-ready gas-fired power plants, each with a minimum capacity of 600 megawatts. These plants are expected to start operations in 2029 and 2030 and are part of Singapore's strategy to meet the anticipated peak power demand of 11.8 gigawatts by 2030.

Vehicle exhausts

The Vehicular Emissions Scheme (VES) and the Commercial Vehicle Emissions Scheme (CVES) have been implemented to encourage the adoption of cleaner passenger and commercial vehicles, respectively. These schemes aim to phase out older, more pollutive commercial vehicles. All new vehicles in Singapore must meet minimum emission standards at the point of registration and while being driven on the roads.

Ozone, a harmful pollutant, is formed when pollutants emitted by cars react chemically in the presence of sunlight. While Singapore has generally maintained good air quality, there have been instances where ozone levels have entered an unhealthy range, impacting air quality and human health. During periods of haze caused by forest fires in the region, PM2.5, a fine particulate matter, becomes the dominant pollutant.

Singapore has adopted an integrated approach to address air pollution, including regular monitoring of emissions from industrial facilities and implementing measures to minimise pollution impacts during land-use planning, development control, and building control stages. The National Environment Agency (NEA) plays a crucial role in monitoring air quality through a network of stations measuring concentration levels of pollutants, including nitrogen dioxide and carbon monoxide, which are commonly associated with vehicle emissions.

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