SINGAPORE: The air quality in Singapore could enter the Unhealthy range in the next 24 hours "if the winds turn unfavourable and the haze situation in Sumatra persists", said the National Environment Agency (NEA) on Thursday (Sep 12).
NEA said it was "slightly hazy" in Singapore on Thursday, with the 24-hour Pollutant Standards Index (PSI) reading falling in the Moderate range of between 75 and 87 at 7pm.
A PSI reading of between 101 and 200 falls in the Unhealthy range.
"The haziness is due to smoke haze from hotspots in central and southern Sumatra being blown in by the prevailing winds," said the agency, adding that slightly hazy conditions were expected for the rest of the day.
A total of 222 hotspots were detected in Sumatra, mostly in the Riau, Jambi and South Sumatra provinces.
"Moderate to dense smoke haze continued to emanate from persistent hotspots there. Some haze has been blown by the prevailing winds across the Strait of Malacca to affect Singapore and some parts of Peninsular Malaysia," said NEA.
In Kalimantan, 1,264 hotspots were detected on Thursday and widespread haze continued to be observed, NEA added.
NEA said "some showers are expected" for Singapore in the next few days, while the weather over Sumatra and Kalimantan will remain "generally dry".
The prevailing winds are forecast to shift to blow from the southwest or south, which may "bring increased haziness" to Singapore.
For the next 24 hours, the one-hour PM2.5 concentration readings are expected to range between Normal and Elevated, said NEA.
"The 24-hr PSI is forecast to be in the Moderate range, and may enter the Unhealthy range if the winds turn unfavourable and the haze situation in Sumatra persists."
NEA advised those who are healthy to reduce prolonged or strenuous outdoor physical exertion, while the elderly, pregnant women and children should minimise such activities.
Those with chronic lung or heart disease should avoid them.
Fires have burnt through parts of Indonesia's Sumatra and Borneo islands for more than a month, and the Indonesian government has sent thousands of security personnel to try to douse the blazes.
The fires are usually started during operations to clear land for palm oil and pulp plantations.
Malaysia said last Friday a diplomatic note would be sent to Indonesia to call for immediate action against the raging fires.
This drew a rebuttal from Indonesia's environmental affairs and forestry minister, who said there has been no recurrence of transboundary haze from Indonesia to neighbouring countries as the number of hotspots has dropped.