Singapore’s air quality worsened on October 9, with the central region’s 24-hour Pollutant Standards Index (PSI) reaching 181, a 2026 high, as smoke from Indonesian wildfires drifted toward the city-state under prevailing winds.
This marked a significant deterioration from earlier readings, as the PSI had previously peaked at 167 on September 29. The 24-hour PSI, which measures six key pollutants, is classified as unhealthy when it exceeds 101, and Singapore’s air quality remained in this range across all five regions throughout the day.
Health Advisories and Regional Air Quality
The National Environment Agency (NEA) issued health advisories urging residents to reduce prolonged outdoor activities as 24-hour PSI readings stayed in the unhealthy range. One-hour PM2.5 readings, which measure fine particulate matter, were elevated across the island, with the west region hitting 171 at 2am—within the “high” pollution band of 151–250. The NEA warned that vulnerable groups, including the elderly and those with chronic illnesses, should avoid strenuous outdoor exertion when PM2.5 levels reached “elevated” (56–150) or “high” (151–250) ranges.
Despite brief periods of “moderate” air quality between 6pm on October 8 and 1am on October 9, all areas returned to the unhealthy range by 2am. The NEA attributed the haze to smoke plumes from southern and central Sumatra and West Kalimantan, noting that dry conditions in Indonesia would likely sustain the issue.
Expert Analysis on El Niño’s Role
Assistant Professor Wang Jingyu of Nanyang Technological University’s National Institute of Education warned that the strong El Niño phenomenon could prolong Singapore’s hazy conditions. In NTU Singapore’s report, he explained that El Niño has extended the dry season in Southeast Asia, delaying the monsoon rains that typically clear pollutants. More substantial relief may arrive only around December,
he said, though he cautioned that any improvement could be short-lived due to the monsoon’s drier phase from late January to March.
The NEA’s forecast for October 8 indicated that the 24-hour PSI would remain in the high moderate to mid-unhealthy
range, with smoke from Indonesia continuing to drift toward Singapore under southeasterly or southerly winds. This aligns with its earlier advisory, which cited persistent dry conditions in Sumatra and Kalimantan as key factors.
Comparative Regional Impact
Singapore overtook Kuala Lumpur as the major city with the worst air quality in the world on Wednesday, October 7, with the Malaysian capital dropping to second place after recording an AQI of 194 on October 8. The Philippine Canadian Inquirer noted that Singapore’s AQI of 211 placed it in the “very unhealthy” category, affecting the general population, not just vulnerable groups. Kuching, Malaysia, ranked eighth with an AQI of 151, while the haze disrupted daily life, including school closures in Johor and disruptions ahead of Singapore’s Formula One event.
Malaysia’s Ministry of Health reported a 259% rise in asthma cases during the last week of August as air quality worsened. Indonesia’s forest fire monitoring service, SiPongi, recorded over 202,000 hectares burned nationwide from January to June, with more than 160 people and 95 companies under investigation for suspected involvement in the fires. The current haze episode, which began on August 1, has affected multiple Southeast Asian nations, with smoke from Sumatra and Kalimantan lingering due to persistent dry conditions.