By Anas Abu Hassan
SINGAPORE, Sept 10 (Bernama) -- Air quality in central Singapore slipped back into the unhealthy range on Thursday, with the 24-hour Pollutant Standards Index (PSI) climbing above the 100-point threshold amid persistent moderate haze.
National Environment Agency (NEA) data showed the 24-hour PSI across the republic ranged from 73 to 105 as at 6 pm, with the central region recording an unhealthy level throughout the day.
Air quality elsewhere remained moderate, with the East recording a PSI of 87, the West at 83, the North (73), and the South (79).
NEA in its haze advisory on Thursday said smoke plumes from southern Sumatra were observed drifting towards Singapore, while moderate to dense smoke plumes continued to be detected from fires in southern Sumatra and Kalimantan.
"As dry conditions are expected to continue over Kalimantan and southern Sumatra, there is a risk of smoke haze affecting Singapore should the fires persist, under the prevailing southeasterly or southerly winds," it said.
The 24-hour PSI indicates Singapore's daily air quality and forms the basis of the NEA's daily health advisories. It is computed based on six air pollutants: PM2.5, PM10, ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide.
-- BERNAMA