Air quality in Singapore worsened on Sept. 26, as the 24-hour Pollutant Standards Index (PSI) reading in the central region crossed back into the unhealthy range. Data provided by the National Environment Agency (NEA) shows that the measurement for that zone reached 104 by 8 p.m., rose to 115 at 11 p.m., and surpassed the 101 mark for the initial time following its exit from the unhealthy bracket on Sept. 20.
Regional readings across Singapore showed distinct variations during the evening hours. At 8 p.m., readings in the north (74), south (78), east (90), and west (88) were in the moderate range. They climbed slightly later—reaching north (80), south (84), east (99), and west (97)—but remained in the moderate range at 11 p.m. Meanwhile, hourly PM2.5 readings, which measure current concentrations of fine particulate matter, entered the elevated band across the entire country by 11 p.m.
Hourly PM2.5 Readings and Regional Spikes
The progression of fine particulate matter showed sharp increases in specific zones during the evening. At 8 p.m., the highest hourly PM2.5 reading was logged in the central area at 110, followed by the east at 88, the west at 82, and the south at 67, while the north stayed in the normal range at 50. By 9 p.m., the central reading spiked to 131, and the north climbed to 69, entering the elevated range.
By 11 p.m., readings in the north (64), south (70), and west (96) declined slightly but stayed within the elevated band. The central area continued to log the highest hourly reading at 124. When the 24-hour PSI falls between 101 and 200, air quality is categorized as unhealthy, whereas an hourly PM2.5 measure of 56 to 150 points to high levels of fine particles.
Did You Know? The PSI first returned to the unhealthy range on Sept. 4, marking the first time the threshold was crossed since October 2023, with readings in the central region eventually peaking at 154 on Sept. 15.
Official Weather Forecast and Haze Advisories
In its daily haze advisory issued at about 6 p.m. on Sept. 26, the NEA projected that air quality for the subsequent 24 hours would range from moderate to low-unhealthy. While showers are forecast over Singapore and parts of the region overnight and into Sept. 27, dry conditions are expected to persist over southern Sumatra as well as southern and eastern Kalimantan.
Winds blowing from the south-east or south-west could carry smoke haze toward Singapore, according to the NEA. The agency advised the public to consult hourly PM2.5 readings for immediate activities and 24-hour PSI figures to plan for the day ahead. During periods when air quality crosses into the unhealthy range, healthy individuals should reduce prolonged or strenuous outdoor activities, while vulnerable groups—including the elderly, children, pregnant women, and people with chronic lung or heart disease—should minimize or avoid such activities altogether.
Frequently Asked Questions
What defines an unhealthy air quality reading in Singapore?
Air quality is considered unhealthy when the 24-hour Pollutant Standards Index (PSI) registers in the range of 101 to 200.
What precautions should vulnerable groups take during unhealthy air conditions?
Vulnerable groups, such as the elderly, children, pregnant women, and individuals with chronic lung or heart disease, are advised to minimize or avoid prolonged or strenuous outdoor activities.
Where is the smoke haze originating from?
The NEA reported that dry conditions over southern Sumatra and southern and eastern Kalimantan, combined with south-easterly or south-westerly winds, could bring smoke haze to Singapore.
How are you adjusting your daily outdoor plans while the haze persists in your neighborhood?