Singapore haze air quality improves with moderate PSI levels

This is in stark contrast to the day before, when unhealthy levels of pollutants were recorded all across the country, a first since September 2019.

Air quality is considered unhealthy when the 24-hour PSI is in the range of 101 to 200, during which the NEA advises the public to reduce outdoor activities. PSI readings of 51 to 100 are considered moderate, while values of zero to 50 are in the “good” range.

The conditions on Sept 15 prompted some organisations such as the Football Association of Singapore to implement measures to mitigate the impact of the haze. 

In an advisory on Sept 15, NEA said air quality in Singapore for the next 24 hours was forecast to be in the high moderate to mid-unhealthy range.

Dry conditions are expected over central and southern Sumatra and southern Kalimantan in neighbouring Indonesia – where forest fires have raged for weeks – in the coming days, NEA added.

“With the prevailing winds forecast to continue blowing from the south-east to east-south-east, there is a risk of smoke haze affecting Singapore,” the agency said.

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

September’s developments mark the first time since October 2023 that the PSI in Singapore hit unhealthy levels because of haze, with the authorities earlier warning of the risk of haze between June and October as a result of warmer and drier conditions brought on by both El Nino and the Indian Ocean Dipole.