SINGAPORE - The skies were mildly hazy on Friday (Sept 18), with the Pollutant Standards Index (PSI) staying within the moderate range.

As of 11pm, the 24-hour PSI was in the moderate range between 83 and 97, while the three-hour PSI was 120. The three-hour reading peaked at 127 at 7pm, after rising throughout the day from below 70 in the morning.

For the rest of the day, the current hazy conditions are expected to persist and may deteriorate slightly, the National Environment Agency's (NEA) said in an update on Friday evening.

It said that the deterioration in the haze conditions on Friday afternoon was due to haze in the surrounding region was being blown in by the prevailing winds.

It added that the 24-hour PSI for the next 24 hours is expected to be in the high end of the moderate range and the low end of the unhealthy range. "For tomorrow (Saturday), the prevailing winds are forecast to blow from the northeast or east. Occasional hazy conditions can still be expected," it said.

A total of 256 hotspots were detected in Sumatra on Friday and moderate to dense haze was observed in southern and central Sumatra, NEA said.

The elderly, pregnant women and children should minimise prolonged or strenuous outdoor physical exertion, while those with chronic lung or heart disease should avoid prolonged or strenuous outdoor physical exertion.

People who are not feeling well, especially the elderly and children, and those with chronic heart or lung conditions, should seek medical attention.

For updates, go to the NEA website, the haze microsite, NEA's Facebook page, Twitter account @NEAsg, or download the myENV app.