SINGAPORE, Oct 7 — Barely a day after air quality improved slightly in northern and southern Singapore, the 24-hour Pollutant Standards Index (PSI) in both regions returned to the unhealthy range.

The 24-hour PSI in northern and southern Singapore crossed into the unhealthy range at 11am.

By 1pm, all five regions recorded unhealthy PSI levels, ranging from 101 to 132.

Meanwhile, one-hour PM2.5 concentrations ranged from 65 to 126, with western Singapore recording the highest concentration reading of 126.

Concentration readings between 56 to 150µg/m3 dall within the elevated band.

The Republic’s 24-hour PSI forecast is expected to be in the high-moderate to mid-unhealthy range, according to the National Environment Agency’s daily haze situation update issued on Tuesday evening.

Neighbouring Malaysia is also experiencing deteriorating air quality. Data from the government’s Air Quality Index Management System at 1.30pm showed that 37 out of 68 monitoring stations recorded unhealthy air quality. — AsiaOne