SINGAPORE – There has been a fourfold increase in hot spots in Sumatra from 15 to 66 on Wednesday, but showers in the region and Singapore will likely keep the 24-hour Pollutant Standards Index (PSI) level in the moderate range.

In the daily haze advisory on Wednesday, the National Environment Agency (NEA) said the 24-hour PSI reading was well within the moderate range – between 58 and 61.

The one-hour PM2.5 reading was between 13 and 28 micrograms per cubic m of air. PM2.5 refers to fine particles – usually airborne – that are 2.5 microns or smaller.

NEA said in its forecast for Thursday that prevailing winds are expected to blow mainly from the south or south-west.

Although drier weather is expected over southern and central Sumatra, the likelihood of transboundary haze is low, owing to expected rain, it added.

NEA on Monday said Singaporeans would be granted a respite from the haze levels from Tuesday due to rain and favourable wind conditions.

Last Saturday, the PSI reading in Singapore went into the unhealthy range for the first time since 2019, with the 24-hour PSI reading falling between 67 and 123 at 9pm.

Residents in the east bore the brunt of the haze, and NEA had advised people to cut down on outdoor activities then.