Singapore woke up to unhealthy air quality in three regions on Saturday, 5 September, as haze continued to affect the country.
At 6am, the 24-hour Pollutant Standards Index, or PSI, stood at 103 in the west and 102 in the east, putting both regions in the unhealthy band. Central Singapore was also recording unhealthy air quality.
By 8am, the central region had a PSI of 117. Conditions in the west and east had improved slightly to 99 and 98 respectively, returning to the moderate range, while the north was at 84 and the south at 87.
PSI First Turned Unhealthy on 4 September
The latest deterioration began a day earlier.
At 7am on Friday, 4 September, central Singapore’s 24-hour PSI reached 101, entering the unhealthy range of 101 to 200. It was the first time Singapore’s PSI had reached unhealthy levels because of haze since 8 October 2023.
The reading continued rising during the day. CNA reported that central Singapore’s PSI reached 123 by 10pm, while the east had also entered the unhealthy range by then. The west followed at midnight on 5 September with a reading of 102.
NEA has since begun issuing daily haze advisories and 24-hour PSI forecasts so people can plan activities for the following day.
Smoke From Sumatra and Kalimantan Drifting Towards Singapore
NEA said the surrounding region was mostly dry on 4 September.
Smoke from fires in southern and central Sumatra, as well as several parts of Kalimantan, was observed moving towards Singapore.
With dry weather expected to continue, NEA said Singapore could remain affected by transboundary haze if the fires persist and prevailing winds continue blowing from the southeast or south.
Its forecast for 5 September placed the 24-hour PSI between the higher end of the moderate range and the middle of the unhealthy range.
The wider regional haze situation has also been elevated. The ASEAN Specialised Meteorological Centre raised its southern ASEAN haze alert to Level 3 on 26 August after widespread moderate to dense smoke haze was observed over parts of Kalimantan and Sumatra.
What You Should Do When PSI Is Unhealthy
When the 24-hour PSI is in the unhealthy range, NEA advises healthy people to reduce prolonged or strenuous physical activity outdoors.
Children, pregnant women and elderly people should minimise prolonged or strenuous outdoor activity, while those with chronic heart or lung conditions should avoid it.
For activities happening immediately, NEA recommends checking the one-hour PM2.5 reading instead, as it gives a more current indication of fine-particle pollution. The 24-hour PSI is more useful for planning activities ahead.
The government also said N95 masks are generally not necessary for brief periods outdoors, such as travelling between home and work or school.
