Hourly PM2.5 readings elevated in two regions; PSI forecast to remain unhealthy on Wednesday
The National Environment Agency said the 24-hour PSI is expected to range from 110 to 180 on Wednesday.
A cyclist rides past the Marina Bay Sands as it's shrouded in haze at midday on Oct 20, 2026. (Photo: CNA/Wallace Woon)
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SINGAPORE: One-hour PM2.5 readings were elevated in Singapore's western and central regions at 11pm on Tuesday (Oct 20), while the other regions recorded readings in the normal band.
Across the five regions, 1-hour PM2.5 readings ranged from 36 to 74.
Air quality in Singapore's west and central regions was unhealthy the entire day, while the northern region remained in the moderate band. The country's east moved into the range at 11am, and the south followed at noon.
At 10pm, air quality in the south returned to the moderate range, with a 24-hour Pollutant Standard Index (PSI) reading of 100.
PSI readings for the other four regions ranged from 86 to 140.
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.
HAZE FORECAST TO REMAIN UNHEALTHY ON WEDNESDAY
In its Tuesday evening advisory, the National Environment Agency (NEA) said air quality in Singapore is forecast to remain unhealthy on Wednesday, with the 24-hour PSI expected to range from 110 to 180.
While showers are expected over Singapore and the surrounding region on Wednesday, smoke haze from fires in Kalimantan may still be blown towards Singapore as winds are forecast to blow from the east-southeast to southeast.
Dry conditions are also likely to persist over southern Kalimantan in the coming days, with prevailing winds potentially carrying more smoke haze towards Singapore.
On Tuesday afternoon, showers were observed in parts of Singapore and the surrounding region. However, residual smoke haze from Kalimantan was seen drifting towards Singapore, while smoke haze was also observed in Sumatra.
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.
