Hourly PM2.5 readings normal in four regions; PSI forecast to remain unhealthy on Thursday
Air quality improved on Wednesday (Oct 21) and by 11pm, only the west's 1-hour PM2.5 reading was in the elevated range.
A view of the haze from central Bishan as air quality shows slight improvement on Oct 21, 2026. (Photo: CNA/Marcus Mark Ramos)
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SINGAPORE: The National Environment Agency (NEA) forecasts unhealthy air quality in Singapore on Thursday (Oct 22), with smoke haze from Kalimantan potentially drifting towards Singapore before a wind shift brings haze from Sumatra over the weekend.
Air quality in Singapore improved on Wednesday, with hourly PM2.5 readings in the normal range in all regions, except the west, by 11pm. The west remained in the elevated band with a reading of 68, while readings across the other four regions ranged from 27 to 54.
Hourly PM2.5 levels in the central region had moved in and out of the normal band since 3am, and its hourly readings peaked for the day at 9am with a reading of 81.
The east entered the elevated band at 6pm after remaining in the normal range since noon. It fell back to normal at 7pm.
Hourly PM2.5 levels in the south were in the normal range for most of Wednesday until they briefly entered the elevated band at 5pm.
The hourly PM2.5 readings were the highest in the west for most of the day, except at 9am when the central region's reading was higher. The region remained in the elevated band for most of the day, while the north stayed in the normal range for almost all of Wednesday.
At 11pm, the 24-hour Pollutant Standards Index (PSI) remained unhealthy in western and central Singapore.
HAZE FORECAST TO REMAIN UNHEALTHY
In its advisory on Wednesday evening, NEA said that air quality in Singapore is forecast to remain unhealthy on Thursday, with the 24-hour PSI expected to range from 101 to 160.
While showers are forecast over Singapore and the surrounding region on Thursday, dry conditions are expected to persist over the southern parts of Kalimantan.
Smoke haze from fires in Kalimantan may be carried towards Singapore by prevailing east-southeasterly or southeasterly winds, NEA said.
On Friday, smoke haze from regional fires may continue to drift towards Singapore under southeasterly or south-southeasterly winds.
Winds are expected to shift towards the southwest on Saturday, potentially bringing smoke haze from Sumatra towards Singapore as dry conditions persist over southern and central parts of the Indonesian island.
On Wednesday afternoon, showers fell mainly over western Singapore, while smoke haze from Kalimantan was observed near Singapore. Smoke haze was also seen over Sumatra.
Singapore saw a brief improvement in air quality on Monday, when PSI readings fell into the moderate range in three of the country's five regions for the first time in more than a week.
Before Monday, the last time Singapore recorded moderate air quality was on Oct 9.
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ADVICE FOR VULNERABLE GROUPS
When the 24-hour PSI is in the unhealthy range, NEA advises the elderly, pregnant women and children to minimise prolonged or strenuous outdoor physical exertion.
People with chronic diseases, including heart or lung conditions, should avoid such activities.
For decisions on mask use and immediate outdoor activities, the public should refer to the one-hour PM2.5 readings instead.
When the 1-hour PM2.5 readings are in the high band, vulnerable individuals, including the elderly, pregnant women and those with chronic heart or lung conditions, should avoid outdoor activities, according to the Ministry of Health (MOH).
Those who need to go outdoors for immediate activities may wear a well-fitting N95 mask or equivalent to reduce their exposure to haze particles.
When 1-hour PM2.5 readings reach the very high band of 251 and above, healthy individuals should also minimise all outdoor activities. Those who need to venture outdoors may similarly use an N95 mask for protection.
However, MOH said N95 masks are generally not needed for commuting between home and school or work, or in indoor environments.
The ministry has also advised the elderly, pregnant women and those with severe heart or lung conditions who experience breathing difficulties to consult their doctor before using an N95 mask.
Those who experience discomfort while wearing one should take a break from using it.
Besides N95 masks, KN95, FFP2 and KF94 masks are also effective in reducing exposure to haze particles, according to MOH.
Members of the public can visit the HazeMaskGoWhere website for more information on collection locations and live updates on mask availability at the vending machines.
MOH had also issued guidance on Oct 13 on the types of masks that can be used for protection against haze.
It said surgical masks can help reduce discomfort and the risk of infections by providing a barrier against larger irritant particles.
However, if PM2.5 readings are above 250 and people need to be outdoors for several hours, MOH recommends wearing an N95 or equivalent mask.
Cloth masks generally do not filter fine particles effectively, although they can reduce discomfort by blocking larger irritant particles in the air.
