SINGAPORE — Air quality in Singapore remained at unhealthy levels on Sunday (Sept 15), a day after the 24-hour Pollutant Standards Index (PSI) surpassed the 100 mark for the first time since August 2016.

As at 12 noon, the 24-hour PSI stood at 119 in the west and south, 108 in the north and central and 107 in the east.

According to the National Environment Agency (NEA), PSI readings of 50 and below denote “good” air quality, “moderate” for 51-100 and “unhealthy” for 101-200.

The one-hour PM2.5 concentration reading ranged from 31 to 49 µg/m3 at noon, within the normal range.

PM2.5 is a measure of tiny particles less than 2.5 micrometres in diameter in the air. When the PM2.5 reading is in the elevated range, haze particles can affect the heart and lungs, especially in people who have chronic heart or lung conditions. Those with such conditions should ensure that they have their medication on hand, NEA said.

According to NEA, one-hour PM2.5 readings are a "good indicator of current air quality", and can be used for those deciding whether to go for immediate outdoor activities, such as a jog.

The PSI reading reached the unhealthy level for the first time on Saturday since August 2016 as it surpassed the 100 mark.

Readings inched up throughout the evening and by midnight.

When air quality is at the unhealthy range, people – especially children, the elderly, pregnant women and those with heart or lung conditions – should reduce prolonged or strenuous outdoor activities. Those who are not feeling well should seek medical attention, NEA said.

NEA has assured the public that there are sufficient stocks of the N95 masks.

"We would like to assure the public that there are sufficient stocks in the warehouses and Government stockpiles," said the agency on Facebook.

"We are working with the retailers to move available stocks to the retail shops, and stocks will be available progressively from today (Sunday)."

HAZY CONDITIONS EXPECTED TO PERSIST

In its media advisory on Saturday evening, NEA said that the air quality worsened in the afternoon due to a confluence of winds over the nearby region that led to more smoke haze from Sumatra being blown towards Singapore.

Hazy conditions are expected to persist for the rest of the day, it added.

And over the next 24 hours, the PSI could enter the mid-section of the unhealthy range if denser haze is blown in.

A total of 450 hotspots were detected mostly in the Riau, Jambi and South Sumatra provinces, said NEA, a sharp increase from the 156 hotpots detected on Friday.

"Moderate to dense smoke haze from persistent hotspots in Riau and Jambi has been blown by the prevailing winds to affect Singapore and the southern parts of Peninsular Malaysia," it noted.

Forest fires have raged through parts of Sumatra and Kalimantan in recent weeks, prompting the Indonesian government to send in military and police to douse the flames.

In Malaysia, air quality dropped to "unhealthy" levels in and around Kuala Lumpur, according to the government's air pollutant index, and the skyline has been shrouded in thick smog. CNA

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