Air quality in central Singapore remains in unhealthy range as PSI hits 105

SINGAPORE – Air quality in central Singapore has remained in the unhealthy range overnight, with the 24-hour Pollutant Standards Index (PSI) in the region at 105 as at 7am on Sept 10.

PSI in the central region had entered the unhealthy range at 11pm on Sept 9, when the PSI hit 102 and continued to creep upwards overnight.

Readings in the north (76), south (78), east (82) and west (86) remained in the moderate range as at 7am on Sept 10.

Haze in Singapore began an uptick again recently when the PSI in the central part crossed 101 early on Sept 4.

Since then, readings in central, eastern and western parts of Singapore have occasionally crossed into the unhealthy range before dipping back into the moderate spectrum.

In an advisory on Sept 9, the National Environment Agency (NEA) said the 24-hour PSI is forecast to range from higher end of the moderate category to the lower end of the unhealthy spectrum.

NEA said that it continues to observe moderate to dense smoke plumes from fires in southern and central Sumatra as well as Kalimantan, adding that some haze also drifted towards Singapore.

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

The recent developments mark the first time the PSI in Singapore hit unhealthy levels due to haze since October 2023.

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.