Hazy conditions back, but stay in moderate range
The haze has returned. At 3pm on Monday, the three-hour Pollutant Standards Index (PSI) average hit 50, and stayed in the "moderate" range in the evening.
The higher pollution levels came after about a week's reprieve, after the PSI hit a one-year high of 79 on Sept 7.
Air quality is considered unhealthy when the index crosses 100.
The hourly reading, given on the National Environment Agency (NEA) website between 7am and 7pm daily, is the average of the previous three hours' air pollution levels.