Air quality in Singapore remains in moderate range as PSI drops to below 100

SINGAPORE – The air quality across Singapore has improved, with the PSI in all five regions of the country falling within the moderate range since 10pm on Sept 10.

The 24-hour Pollutant Standards Index (PSI) for the central region stayed within the moderate range overnight, after reaching unhealthy levels when it hit a high of 106 between 9am and 11am on Sept 10.

As at 7am on Sept 11, the PSI in central Singapore was 97, with the readings in the other regions also in the moderate range, according to the National Environment Agency (NEA) website.

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

Since then, readings in the 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 10, NEA said the 24-hour PSI is forecast to range from the 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.

It added that while “some showers are forecast mostly over northern and central Sumatra in the next few days... there is a risk of smoke haze affecting Singapore should the fires persist under the prevailing south-easterly or southerly winds”.

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.