Air quality in all regions in Singapore hit unhealthy range
Dry conditions are expected to persist over southern Sumatra and Kalimantan and smoke haze could continue to drift towards Singapore, NEA said.
A view of the haze in central Bishan on the afternoon of Oct 5, 2026. (Photo: CNA/Marcus Mark Ramos)
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SINGAPORE: Air quality in all regions in Singapore entered the unhealthy range on Monday (Oct 5) night.
The 24-hour Pollutant Standards Index (PSI) reading hit 128 in the central region, 125 in the west and 109 in the east at 9pm.
The north and south of Singapore also entered the unhealthy range after it had remained in the moderate zone earlier on Monday. Its PSI reading hit 103 and 101 at 9pm respectively.
The 1-hour PM2.5 reading, which gives a more current indication of air quality, was elevated across Singapore at 9pm.
For immediate outdoor activities, people should refer to the 1-hour PM2.5 readings and corresponding personal guide, the National Environment Agency (NEA) said.
The 24-hour PSI forecast and health advisories should be used when planning outdoor activities for the next day.
When 1-hour PM2.5 levels are raised, healthy people are advised to reduce strenuous outdoor activity for the next hour, while elders, pregnant women, children and people with chronic heart or lung conditions should avoid such activity.
In an update on Monday evening, NEA said clusters of scattered hotspots were detected in the southern parts of Kalimantan, while isolated hotspots were detected in southern Sumatra and Sulawesi.
Moderate to dense smoke plumes in the southern parts of Sumatra were observed drifting north into parts of Peninsular Malaysia and Singapore, while moderate to dense smoke haze was also observed in parts of Kalimantan.
Dry conditions are expected to persist over the southern parts of Sumatra and Kalimantan. With prevailing winds expected to blow from the southeast or east-southeast, smoke haze could continue to drift towards Singapore, NEA said.
The hotspot and smoke haze situation is expected to remain escalated, with a continued risk of transboundary haze.
The deterioration in Singapore's air quality had been anticipated. NEA said on Sunday that the 24-hour PSI for Monday was forecast to be in the high end of the moderate range to the low end of the unhealthy range.
NEA forecast the 24-hour PSI for Singapore to be in the high-moderate to mid-unhealthy range over the next 24 hours.
The 24-hour PSI is Singapore's indicator of daily air quality and forms the basis of NEA's daily health advisories. It is calculated using six air pollutants - PM2.5, PM10, ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide - and reflects the average air quality of the past 24 hours.
The 1-hour PM2.5 reading, on the other hand, is the hourly average of the PM2.5 pollutant levels. PM2.5 is fine particulate matter with a diameter of 2.5 micrometres or shorter, and is the dominant pollutant during haze that causes harm to health.
A 24-hour PSI reading is considered "unhealthy" when it is in the 101 to 200 range, "very unhealthy" when it is within the 201-300 range and "hazardous" when it goes over 300.
The hourly PM2.5 reading is classified in four bands: normal, elevated, high and very high. It is considered elevated when it ranges from 56 to 150. The "high" band ranges from 151 to 250, and readings above that are classified as "very high".
