(Source: www.straitstimes.com)

SINGAPORE – The 24-hour Pollutant Standards Index (PSI) was at the high end of the moderate range on Friday (April 21), reaching 95 in the south at 8am.

As of 2pm, it was highest in the south of the island at 89. A PSI reading of 100 indicates unhealthy air quality, while a reading of 51 to 100 means moderate air quality.

In the east, it reached 83, and in the north, 80. It was 59 in the west and 77 in the central region.

The PSI was inching upwards since Thursday but the National Environment Agency (NEA) said in a late morning update that there were no significant hotspots or smoke haze detected in the nearby region.

“The haziness was due to the accumulation of particulate matter under light wind conditions,” it said.

The likelihood of transboundary haze affecting Singapore in the coming days is low, the agency told The Straits Times.

Asia Pulp & Paper Company said there are currently no fires in their supply chain and they are continuing to actively monitor the situation in and around their suppliers’ concession borders.


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How to interpret one-hour PM2.5 readings

The one-hour PM2.5 reading was between three and eight, which is normal (Band I).

Band I, ranging from 0 to 55, is normal while Band II (56 to 150) is elevated.

A Sumatra squall in the morning helped to clear the hazy conditions, NEA said. The rest of the day is expected to be cloudy with light rain clearing in the afternoon.

The PM2.5 concentration readings are an indicative measure of the current air quality and can be used to plan one’s immediate activities.

Most people can continue their normal activities while the 24-hour PSI is moderate, according to NEA website.

More Info: www.straitstimes.com