Singapore's hourly PM2.5 levels normalize while 24-hour PSI stays unhealthy
On the morning of Oct 25, hourly PM2.5 readings fell to normal levels across Singapore, but 24-hour PSI values remained in the unhealthy range for most regions.
Singapore's air-quality monitoring on Oct 25 showed hourly PM2.5 concentrations returning to the normal band (31-48 µg/m³) across all five regions, while 24-hour Pollutant Standards Index (PSI) readings stayed mostly in the unhealthy range, ranging from 107 to 132. Only the southern region recorded a PSI of 100, classified as good to moderate.
The National Environment Agency (NEA) noted that PM2.5 levels had been elevated since the evening of Oct 24 and that the PSI, which averages six key pollutants over 24 hours, indicates unhealthy air when it exceeds 100. The agency advises vulnerable groups—elderly, children and those with health conditions—to limit outdoor activities when the unhealthy threshold is crossed.
NEA had earlier warned that moderate to unhealthy conditions were expected on Oct 25, forecasting PSI values between 80 and 130. Smoke haze from Sumatra and Kalimantan was observed drifting toward Singapore on Oct 24. The agency added that south-west or west winds and expected showers on Oct 25-27 should help reduce haze and improve air quality.
"The haze situation is likely to improve with the expected winds and showers," NEA said.