SINGAPORE: Visibility in some parts of Singapore was reduced to between 3km and 5km on Monday morning (Sep 23) due to hazy conditions and increased moisture in the atmosphere, said the National Environment Agency (NEA).
This gradually improved to a visibility of between 7km and 8km over most areas in the afternoon, the agency added.
Air quality improved slightly as well compared to Sunday, after showers over Singapore and the surrounding sea areas.
At 8pm, the 24-hour Pollutant Standards Index (PSI) was 92 in the north, 97 in the central region, 98 in the west, 99 in the east and 107 in the south - mostly in the moderate range.
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 readings at 8pm ranged between 39-57µg/m3. It was in the normal band for most parts of Singapore.
Showers fell over northern and central Sumatra as well as western Kalimantan on Monday, NEA noted.
Sixty hotspots were detected in Sumatra, mostly in the provinces of Riau, Jambi and South Sumatra, down sharply from the 246 detected on Sunday due to cloud cover over Sumatra, the agency added.
In Kalimantan, however, a total of 1,006 hotspots were detected.
"Some showers over western Kalimantan have helped to improve the hazy conditions there, but smoke haze continued to be observed in southern Kalimantan," said NEA.
On Tuesday, the air quality is expected to further improve as thundery showers are forecast in the late morning and early afternoon.
For the next 24 hours, the one-hr PM2.5 concentration readings are expected to be in the normal band but may occasionally enter the elevated band under light wind conditions, said NEA.
It added that the 24-hr PSI is forecast to be in the low end of unhealthy range and is expected to gradually improve to the high end of moderate range.