(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) morning, possibly heralding the return of the haze to Singapore.

As of 7am, it was highest in the south of the island at 93. A PSI reading of 100 indicates unhealthy air quality, while a reading of 51 to 100 means moderate air quality.

The PSI has been inching upwards since Thursday.

In the east, it reached 87, and in the north, 84. It was 62 in the west and 79 in the central region.

The one-hour PM2.5 reading was mixed. It was between 35 and 57 (Band I) in the west, north and central areas, 55 in the east and 57 in the south (Band II).

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

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.

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