Singapore air quality returned to moderate levels early on Sept 28 after the 24-hour Pollutant Standards Index (PSI) climbed into the unhealthy band a day earlier. The central region registered a 24-hour PSI reading of 80 at 6am on Sept 28, following a peak of 110 on Sept 27 that forced adjustments to outdoor sporting events.
Regional PSI Readings and Air Quality Recovery
By the morning of Sept 28, all regions across Singapore recorded 24-hour PSI figures safely within the moderate range of 51 to 100. The northern region stood at 62, the southern area at 68, the eastern zone at 74, and the western sector at 68 alongside the central region’s 80.
This marked a recovery from Sept 27, when air quality deteriorated across parts of the island. At 7am on Sept 27, the 24-hour PSI readings hit 128 in the central region, 115 in the east, and 106 in the west, while the north recorded 89 and the south reached 95. Air quality is classified as unhealthy when the 24-hour PSI ranges between 101 and 200.
Improvement began late on the night of Sept 27. By 9pm, the east dropped to 99, slipping below the 101 unhealthy threshold. Midnight brought further relief as the central region’s PSI fell to 95, pulling the entire island back into moderate air quality levels.
Impact on Outdoor Events and Public Health Advisories
The worsening air quality forced organizers to alter Decathlon’s inaugural Kiprun race on Sept 27. The event’s 21.1km half-marathon was shortened to 10km, though distances for the standalone 10km, 5km, and 670m Kids Dash formats remained untouched.
In its daily haze advisory issued on Sept 27, the NEA forecast that Singapore’s air quality for the subsequent 24 hours would hover between the moderate and low-unhealthy range. The agency advised healthy individuals to reduce prolonged or strenuous outdoor exertion whenever readings cross into the unhealthy band. Vulnerable populations—including the elderly, children, pregnant women, and people with chronic lung or heart disease—were urged to minimize or entirely avoid outdoor physical activities.
The NEA also recommended that the public consult hourly PM2.5 readings for immediate outdoor decisions while using 24-hour PSI metrics to plan daily schedules. An hourly PM2.5 concentration between 56 and 150 denotes an elevated presence of fine particulate matter.
Looking at broader environmental trends, September marked the first time since October 2023 that Singapore recorded unhealthy PSI levels due to haze. The central region previously peaked at 154 on Sept 15. While the Meteorological Service Singapore noted in its fortnightly weather forecast on Sept 16 that increased showers would arrive in the second half of the month, the NEA cautioned that dry conditions persist over southern Sumatra and southern Kalimantan. With prevailing winds forecast to blow from the south-east, officials warned that smoke haze continues to pose a risk to Singapore.
Frequently Asked Questions about Singapore’s Haze Situation
What caused the recent haze in Singapore?
Prevailing winds blowing from the south-east carried smoke haze from fires in southern Sumatra and southern Kalimantan, where dry conditions continue.
What is the difference between the 24-hour PSI and hourly PM2.5 readings?
The 24-hour Pollutant Standards Index is computed using the daily average concentration of six pollutants to help plan for the day ahead. Hourly PM2.5 measurements indicate immediate fine micro-pollutant levels and should be checked right before heading outdoors.
Who is most at risk when air quality drops to unhealthy levels?
Vulnerable groups, including the elderly, children, pregnant individuals, and people with pre-existing chronic heart or lung conditions, are advised to minimize or avoid strenuous outdoor activities.
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