Singapore experienced a brief respite from worsening air pollution on September 6, 2024, as 24-hour Pollutant Standards Index (PSI) readings returned to moderate levels across all five regions, according to the National Environment Agency (NEA). However, authorities warned that transboundary smoke could return if fires in neighboring Indonesia persist.
PSI Readings Return to Moderate Range
Air quality improved significantly by the morning of September 6, following a day where pollution breached the unhealthy threshold in three parts of the island, according to data reported by CNA. As of 7:00 AM, the NEA confirmed that all regional readings sat comfortably within the moderate band.
The central region dropped to a PSI of 91 by midnight, down from a peak of 123 at 1:00 AM the previous day. The west and east regions also recovered, recording readings of 86 and 77 respectively at midnight, after briefly entering the unhealthy bracket at 6:00 AM on September 5 when the west reached 103 and the east hit 102. The north and south maintained moderate levels throughout the episode, registering 75 and 72 respectively at midnight.
Breakdown of Singapore Air Quality Readings
| Region | Peak PSI (Sept 5) | Midnight PSI (Sept 5/6) | Status (Sept 6, 7am) |
|---|---|---|---|
| Central | 123 (at 1:00 AM) | 91 | Moderate |
| West | 103 (at 6:00 AM) | 86 | Moderate |
| East | 102 (at 6:00 AM) | 77 | Moderate |
| North | 75 (throughout) | 75 | Moderate |
| South | 72 (throughout) | 72 | Moderate |
Triggering Thresholds and Haze Advisories
The temporary spike marked Singapore’s first breach of the unhealthy PSI threshold since October 8, 2023. When the 24-hour PSI crossed above 100 at 7:00 AM on Friday, September 5, the NEA initiated daily haze advisories containing 24-hour forecasts to help residents plan outdoor events.
The 24-hour PSI evaluates six pollutants, with fine particulate matter—known as PM2.5—typically acting as the dominant pollutant during regional haze events. Under official classifications, a PSI reading between 101 and 200 counts as unhealthy, 201 to 300 is very unhealthy, and any figure surpassing 300 is considered hazardous.
Weather Patterns and Ongoing Smoke Threat
Despite the morning improvement, the NEA cautioned that clean air might prove temporary. In its Saturday advisory, the agency stated that Singapore could face renewed transboundary haze if fires in Indonesia remain active. Forecasters predict PSI levels will range from the higher end of moderate to the lower end of unhealthy.
Satellite data showed moderate to dense smoke plumes drifting from southern and central Sumatra as well as parts of Kalimantan toward Singapore. With surrounding areas remaining dry, the NEA expects dry weather to persist alongside prevailing winds blowing from the southeast or south. In response to the shifting conditions, agencies under Singapore’s Haze Task Force activated respective action plans and public health advisories.
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