1-hour PM2.5 in west of S'pore hits 171 overnight, within high range

The air quality across Singapore continued to worsen over the early hours of Oct. 9.

According to the National Environment Agency (NEA) website, the overall 24-hour Pollutant Standards Index (PSI) reading was between 102 and 147 at 2am, within the unhealthy range.

It climbed to between 117 and 173 by 10am.

At 9am, the central region logged a 170 24-hour PSI reading, the highest recorded in Singapore in 2026, according to CNA.

When 24-hour PSI readings are in the unhealthy range, the NEA advises the public to reduce prolonged or strenuous outdoor physical exertion.

Haziest in the west

Based on the one-hour PM2.5 readings, the west was the haziest region in the country for most of the night.

It hit 171 at 2am, within the high range that is between 151 and 250.

However, the readings fluctuated afterwards and finally dipped to 114 by 10am, returning to an elevated range.

Central Singapore remained in the high range from 11pm to 2am, with the highest reading at 163 at 11pm.

The numbers gradually dropped, but rose slightly at 10am to 142, up from 137 an hour before.

Readings for the rest of the country largely remained in the elevated range.

The one-hour PM2.5 concentration readings serve as a real-time gauge of the air during hazy conditions, thus providing the most current indication of air quality.

When they are in the elevated range, the NEA advises healthy people to reduce strenuous outdoor activity for the next hour.

The elderly, pregnant women, children, and people with chronic heart or lung conditions should avoid such activity.

Smoke plumes from Indonesia

On Oct. 8, the NEA posted on Facebook that moderate to dense smoke plumes from southern and central Sumatra and West Kalimantan were observed to drift towards Singapore.

The agency believes that the prevailing southeasterly or southerly winds may continue to send smoke haze drifting towards Singapore.