SINGAPORE — As at 9am today (Sept 15), the 24-hr Pollutant Standards Index (PSI) is 105 in the Western Region of Singapore, and 78 to 84 for the other regions.

The PSI three-hour reading reached a peak of 113 earlier this morning (Sept 15) at 6am.

The National Environment Agency (NEA) says elevated levels of PM2.5 were recorded from 10pm last night to 7am this morning, with the most severe conditions in the western half of Singapore.

The NEA explains that the elevated levels of PM2.5 are likely due to the hotspots in South Sumatra detected over the past three to four days.

Given the continued dry weather in southern Sumatra, the 24-hour PSI for Singapore is likely to fluctuate between the high end of the Moderate range and the low end of the Unhealthy range for the rest of the day, the NEA added.

A PSI reading of 0-50 is “good”, 51-100 is “moderate”, while 101-200 is considered “unhealthy”.

The NEA advises on its website that healthy people reduce prolonged or strenuous outdoor physical exertion when the PSI is in the “unhealthy” range. The elderly, pregnant women and children should minimise such activities, which should also be avoided by people with chronic lung disease or heart disease.