SINGAPORE – The chance of the haze affecting the Republic is expected to remain low with more showers forecast here and in the region for the next few days, said the National Environment Agency (NEA) on Monday evening (Sept 30).

For the next 24 hours, the authority said, the one-hour PM2.5 concentration readings are expected to be in the normal band, while 24-hour Pollutant Standards Index (PSI) should be in the moderate range.

A PSI reading of zero to 50 indicates good air quality, while a reading of 51 to 100 is in the moderate range. A reading of 101 to 200 is considered unhealthy, very unhealthy from 201 to 300, and hazardous when the reading is more than 300.

The PM2.5 concentration scale, which the NEA has said is a better measure of current air quality, has four bands: 0 to 55 for normal, 56 to 150 for elevated, 151 to 250 for high, and very high for any higher readings.

As for Monday, there were showers over many areas in Sumatra, except in the southern provinces. NEA said the showers have helped to improve the hot spot situation in Sumatra, with 90 hot spots detected on Monday, mostly in south Sumatra.

There were also thundery showers over many parts of Singapore, and at 6pm on Monday, the 24-hour PSI reading was 50-58, in the good to moderate range. The PM2.5 reading was 20-32, in the normal band.

The environment agency has said that the health impact of the haze is dependent on one’s health status, the PSI level and the length and intensity of outdoor activity.

Doctors The Straits Times has spoken to have warned that vulnerable groups, such as patients with pre-existing medical conditions, could experience increased discomfort on poor air quality days.