SINGAPORE — Air quality in Singapore improved in 2020, with the decrease in economic and transport activities due to Covid-19 contributing to this improvement, said a report on Singapore's environment.

The air quality in Singapore was in the Good to Moderate range on all days of 2020, according to the inaugural State of the Environment: Air and Water Quality Report published by the National Environment Agency (NEA).

The relatively wet weather during the traditional dry season in the second half of 2020 also helped to keep pollutant levels down, said NEA.

The "circuit breaker" period saw a 28.8 per cent reduction in the atmospheric levels of fine particulate matter or PM2.5, a 38.1 per cent reduction in nitrogen dioxide, a 5.6 per cent reduction in carbon monoxide, and 58.1 per cent reduction in sulphur dioxide over levels in the same time period in the previous three years.

POLLUTANTS MONITORED IN SINGAPORE

The ambient air quality in Singapore is continuously monitored through a network of air monitoring analysers. These sensors measure the level of six criteria air pollutants: Sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and particulate matter (both PM10 and PM2.5), and a variety of volatile organic compounds.

NEA primarily benchmarks Singapore’s air quality against the World Health Organization's Air Quality Guidelines.

While Singapore was able to meet the WHO limits for nitrogen dioxide and carbon monoxide, the limits for particulate matter (PM10 and PM2.5), sulphur dioxide and ozone were exceeded, the report said.

Particulate matter (PM10 and PM2.5): In 2020, the annual mean PM10 and PM2.5 levels exceeded WHO guidelines. However, they were the lowest recorded over the last 10 years.

Apart from the elevated levels in years affected by severe transboundary haze, the trend shows that the levels of PM10 and PM2.5 have been decreasing over the past decade.

Sulphur dioxide: Singapore’s maximum 24-hour SO2 mean in 2020 was 30 µg/m3, the lowest over the past 10 years. However, this is still above WHO guidelines of 20 µg/m3.

Industrial and shipping activities are the main sources of Singapore’s SO2 emissions. The reduction of industrial activities was the likely key reason for the improved performance.

Nitrogen dioxide: The annual NO2 mean of 20 µg/m3 n 2020 was the lowest it has been in the last 10 years.

Singapore has been meeting the WHO baseline of 40 µg/m3 over the past decade.

Carbon monoxide: Singapore’s maximum 8-hour mean for CO in 2020 was 1.2 mg/m3, well within the WHO standard of 10 mg/m3. It was also the lowest recorded concentration over the last 10 years.

WATER QUALITY

For water quality, Singapore's inland, coastal, and recreational beach waters, have met their respective water quality guidelines.

Seven popular beaches achieved a Good banding on NEA’s recreational water quality guidelines, consistent with primary contact recreational activities.

These activities are those that involve immersion in water, such as swimming, windsurfing and other water sports.

Mr Ram Bhaskar, NEA's deputy chief executive officer (environmental protection) and director-general of environmental protection said: “We enjoy clean ambient air and inland and coastal waters throughout most times of the year.

"This is achieved through a multi-prong pollution management strategy comprising upstream planning controls, surveillance and enforcement, and downstream environmental monitoring.

"The state of our air and water quality serves as a gauge in assessing the effectiveness of the pollution management strategies and drives policy reviews, as we continue to strive towards achieving international environmental standards."

NEW MONITORING TECHNOLOGIES

NEA said it has been conducting trials of new monitoring technologies, including the use of low-cost air quality sensors. These sensors will provide a higher spatial resolution of the dispersion of air pollutants, added NEA.

The low cost and portability of the sensors make it possible to obtain air quality measurements in more locations, such as along roadsides, in areas where there is high pedestrian activity, or near sources of pollution that may not have space to site an air quality monitoring station.

The agency is also collaborating with research institutions to "tap on additional scientific support".

For example, there is a project with the National University of Singapore’s Environmental Research Institute (Neri) to better determine if smoke haze incidents could be due to peatland burning.

During the 2019 haze episode, the peat forest smoke indicator developed by Neri was used and it established that PM2.5 mainly originated from peatland burning in the region, as analysis conducted on it revealed higher fractions of the unique ratios of organic carbon in the carbonaceous profile of PM2.5. CNA

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