The Pollutant Standards Index (PSI) on Monday afternoon climbed to a three-hour average of 47 at 2pm as people around Singapore complained of hazy conditions and a burning smell in the air.
The three-hour average PSI at 1pm was 43, while that at noon was 39, indicating it was on the rise although still in the "good" range. The PSI is a measure of air quality.
The National Environment Agency's advisory for Monday said that Singapore may experience slightly hazy conditions in the morning due to the accumulation of particulate matter under light wind conditions.
Minister for Environment and Water Resources, Vivian Balakrishnan, said on his Faceboko page that the visible haze is due to south-west winds blowing from hotspots in Riau and local accumulation over Singapore. "Fortunately, the situation should improve as rain is forecasted over the next few days to douse the fires in Riau. The southerly wind will also be strengthening," he added.
On Sunday, satellite maps recorded 33 hot spots in Sumatra, but others could be obscured by cloud cover. On September 24 however, 281 hot spots were recorded there. Last week, Asean environment ministers at a meeting in Indonesia recommended that their leaders agree to a joint haze monitoring system and sharing of maps to pinpoint those responsible for burning, after parts of the region were overwhelmed by record haze in June.