3-hour PSI hits 137; 24-hour PSI edges into unhealthy range of 101-111

Update: The 24-hour PSI reading at 3pm is between 104 and 113, while the 3-hour PSI lowered slightly to 132.

The haze has worsened with the 3-hour Pollutant Standards Index (PSI) hitting 137 as at 1pm on Thursday (Sept 10).

The latest 24-hour PSI at 1pm was between 101 and 111. A 24-hour PSI reading of above 100 is considered unhealthy.

On Wednesday (Sept 9), the PSI readings were lower, with the 24-hour PSI at 7pm ranging between 69 and 77 in the high end of the Moderate range.

Thundery showers yesterday improved air quality slightly, but hazy conditions are expected to continue through Thursday, said NEA in an advisory on Wednesday.

A total of 140 hotspots were detected in Sumatra, said NEA. Hazy conditions will persist as prevailing winds are forecast to blow from the south and southwest. Showers are forecast for Singapore in the late morning and early afternoon on Thursday.

"The 24-hour PSI for the next 24 hours is expected to be in the high end of the Moderate range and low end of the Unhealthy range, and may further deteriorate if the winds are unfavourable," NEA added.

The elderly, pregnant women and children should minimise prolonged or strenuous outdoor physical exertion. Those who feel unwell should seek medical attention.