Air quality in Singapore improved on the morning of Oct 25. At 7am, hourly PM2.5 readings were back in the "normal" range in the north (55), south (44) and central (54) regions. The east (61) and west (62) remained "elevated". The 24-hour PSI, however, was still "unhealthy" everywhere: 111 in the north, 104 in the south, 112 in the east, 140 in the west and 115 in the central region.
In its evening advisory on Oct 24, the National Environment Agency (NEA) forecast moderate to unhealthy air quality for Oct 25, with the PSI in the range of 80 to 130. NEA said smoke haze from Sumatra was seen drifting towards Singapore on Oct 24.
What the two sets of readings mean for families
- PM2.5 is gauged hourly and shows current air quality, while the PSI is a 24-hour rolling average of six key air pollutants.
- PM2.5 from 0 to 55 is "normal" and 56 to 150 is "elevated"; PSI of 0 to 100 is good to moderate and 101 to 200 is unhealthy.
- NEA expects south-west or west winds and showers from Oct 25 to 27, and says the haze is "likely to improve" on Oct 26 and 27.
If the PSI is in the unhealthy band
- Scale down outdoor activities once air quality passes the "unhealthy" threshold, especially for children, the elderly and people with health issues, as the report advises.