Singapore PSI unhealthy in all regions; central peaks at 164

By 7am on Tuesday (Sept 29), every region of Singapore had crossed into the unhealthy band for the 24-hour Pollutant Standards Index, CNA reported. The Straits Times said the central region's reading then climbed to a season-high 164 at 10am.

The climb started Monday night. The central and south regions first entered unhealthy territory at 8pm with 24-hour PSI readings of 104 and 103, CNA reported. The west followed at 9pm with 101, and the east at midnight with 103. The north was last, reaching 101 at 7am, which left all five regions unhealthy for the first time since Sept 15.

How the readings moved through the morning

The central region's PSI was 155 at 7am, up from the previous season high of 154 on Sept 15, The Straits Times reported. It then reached 164 at 10am. Hourly PM2.5 readings, which track immediate conditions, were elevated across the island as of 9am, ranging from 61 to 112, CNA said. The Straits Times reported that PM2.5 levels had peaked between 85 and 165 at midnight before easing.

A 24-hour PSI reading of 101 to 200 is classified as unhealthy. An hourly PM2.5 reading between 56 and 150 is elevated.

What residents and officials said

Residents shared discomfort online. Prettyplushy Jamm, posting pictures of the smog on Facebook, said she "didn't even dare to open the windows." Jalan Besar GRC MP Shawn Loh said in a Facebook post that Residents' Network centres in Whampoa-Boon Keng, which are fully air-conditioned, are open daily from 10am to about 9pm. Whampoa and Kallang Community Centres also offer shelter from the haze during those hours, he said.

What NEA expects next

The National Environment Agency (NEA) said dry conditions are expected to persist over southern Sumatra and parts of Kalimantan, where fires have produced moderate to dense smoke haze drifting toward Singapore. Showers are forecast for Singapore on Sept 29, but prevailing winds from the east or south-east may still carry smoke haze over the island. NEA's 24-hour PSI forecast was for high moderate to mid-unhealthy air quality.

For unhealthy periods, NEA advised healthy people to reduce prolonged or strenuous outdoor activities. Elderly people, children, pregnant women, and people with chronic lung or heart disease should minimise or avoid such activities altogether.