Haze in S’pore: Air quality improved slightly but PSI in most areas still in unhealthy range

SINGAPORE - Air quality across Singapore improved slightly overnight but remained largely in the unhealthy range.

As at 6am on Sept 30, the 24-hour Pollutant Standards Index (PSI) readings in the central, eastern, western and southern regions stood at 121, 119, 121 and 112 respectively while the air quality in the northern part of the island inched downwards to the moderate range at 97.

This comes after the 24-hour PSI breached the unhealthy band on Sept 29 for the first time in two weeks.

It peaked at 167 at 12pm that day in the central region, a new high since the PSI first returned to the unhealthy range due to the haze on Sept 4.

At 6am on Sept 30, the one-hour PM2.5 readings, which are used as a gauge for immediate activities, remained in the elevated range in the central (64), eastern (67) and western (67) regions, while the northern and southern regions saw readings dropped to 53 and 52 respectively, in the normal range.

Air quality is considered unhealthy when the 24-hour PSI is between 101 and 200, while an hourly PM2.5 reading between 56 and 150 indicates an elevated concentration of fine particles.

In its daily haze advisory at about 6.20pm on Sept 29, the National Environment Agency (NEA) said air quality in Singapore for the next 24 hours was forecast to be in the high moderate to mid-unhealthy range.

It said that dry conditions are expected to persist over southern Sumatra and parts of Kalimantan.

While showers are forecast over Singapore on Sept 30, smoke haze may still affect the island with the prevailing winds expected to blow from the east or south-east, NEA said.

For periods when the air quality crosses into the unhealthy range, NEA has advised healthy people to reduce prolonged or strenuous outdoor activities, while vulnerable groups like the elderly, children and pregnant women, as well as people with chronic lung or heart disease, should minimise or avoid such activities altogether.

The PSI first returned to the unhealthy range due to the haze on Sept 4, the first time since October 2023.

In its fortnightly weather forecast on Sept 16, the Meteorological Service Singapore said more showers are expected in the second half of the month than in the first.