Air quality in Singapore’s central region back in unhealthy range as PSI hits 102

SINGAPORE – Air quality in the central region here has entered the unhealthy range again on Sept 14, with a 24-hour Pollutant Standards Index (PSI) reading of 102.

According to official readings from the National Environment Agency (NEA), the 24-hour PSI as at 12pm was 91 in the east and west, 82 in the south and 79 in the north.

The PSI crossed into the unhealthy range two weeks ago, hitting 101 in central Singapore on the morning of Sept 4. In the following days, readings in the central, eastern and western parts of Singapore occasionally crossed into the unhealthy range.

PSI readings across the island have fallen back into the moderate spectrum and have remained there since Sept 11.

The recent developments mark the first time the PSI in Singapore hit unhealthy levels due to haze since October 2023, with the authorities earlier warning of the risk of haze between June and October due to warmer and drier conditions brought on by both the El Nino and the Indian Ocean Dipole.

In an advisory on Sept 14, the National Environment Agency said air quality for the next 24 hours is forecast to be in the moderate and in the lower end of the unhealthy range.

It said moderate to dense smoke plumes, some of which were observed to be drifting towards Singapore, continue to be observed from fires in Kalimantan.

Smoke plumes were also observed in southern Sumatra.

Showers are forecast over northern Sumatra and north-western Borneo in the coming days, and dry weather conditions are expected to persist over Kalimantan and central and southern Sumatra.

“With the prevailing winds blowing from the south-east or south, there remains a risk of smoke haze affecting Singapore,” said NEA.

Air quality is considered unhealthy when the PSI is in the range of 101 to 200, during which NEA advises the public to cut down on outdoor activities.

PSI readings of 51 to 100 are considered moderate, while values of 0 to 50 are in the “good” range.