SINGAPORE - The haze is expected to clear up slightly heading into Sunday (Sept 20), said the National Environment Agency (NEA) in its latest advisory on Saturday evening.

"The 24-hour Pollutant Standards Index (PSI) for the next 24 hours is expected to drop from the mid-section of the unhealthy range to the low end of the unhealthy range and the high end of the moderate range," the statement said.

As of 11pm, the 24-hour PSI was between 116-141, while the 3-hour PSI was recorded in the high end of the moderate range at 90.

NEA added that the hazy conditions in Singapore have been gradually improving since Saturday evening, due to a shift in the prevailing winds to blow from the east-northeast.

But the situation could possibly worsen on Sunday should denser haze from the surrounding region be blown in by unfavourable winds.

Given the air quality forecast for the next 24 hours, healthy people should reduce prolonged or strenuous outdoor physical exertion, it cautioned.

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, visit the NEA website, NEA's Facebook page, Twitter account (@NEAsg), or download the myENV app.