Haze watch: PSI remains in moderate range, thundery showers expected in afternoon

For a second consecutive morning, residents in the Republic on Tuesday (Sept 22) woke up to moderate air quality in Singapore.The central, eastern and western regions, which recorded unhealthy air quality on Sunday, returned to the moderate range the same day, and has stayed that way since.At 9am, Singapore's 24-hour Pollutant Standards Index (PSI) ranged from 61 to 81 — in the moderate range — with central Singapore recording the highest PSI reading of 81.Meanwhile, one-hour PM2.5 concentration readings across all five regions are in the normal band. PSI forecastIn its daily haze update on Monday evening, the National Environment Agency (NEA) said it expects the 24-hour PSI forecast to be in the moderate to low-unhealthy range.It added that the risk of smoke haze affecting Singapore remains due to the prevailing south-easterly winds.Moderate to dense smoke plumes were observed from fires in Kalimantan and southern Sumatra during its weather satellite's pass on Monday afternoon.