Air quality in central region enters unhealthy range again with 24-hour PSI readings of 102-103

SINGAPORE - Air quality in Singapore worsened on Sept 17, with 24-hour Pollutant Standards Index (PSI) reading in the central region crossing into the unhealthy range again.

The 24-hour PSI reading for that area hit 102 at 9pm, after a reprieve the day earlier where readings across Singapore fell into the moderate range from 11am onwards.

As at 9pm, readings in the north (72), south (70), east (81) and west (93) remained in the moderate range.

Hourly PM2.5 readings, which indicate the current concentrations of fine particulate matter, are in the normal band for the north (55) and south (40), and east (51), and in the elevated band in the west (64) and central (93) as at 9pm.

The National Environment Agency (NEA) has advised the public to refer to the hourly PM2.5 readings for immediate activities and 24-hour PSI ones to plan for the day ahead.

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

During such periods, the NEA has advised those who are healthy to reduce prolonged or strenuous outdoor activities, while vulnerable groups like the elderly, children, pregnant women as well as people with chronic lung or heart disease should minimise or avoid such outdoor activities altogether

The PSI had first returned to the unhealthy mark two weeks ago on Sept 4, the first time since October 2023. Readings in the central region were the highest, peaking at 154 on Sept 15.

With dry conditions persisting over parts of Indonesian hotspots Sumatra and Kalimantan, coupled with prevailing winds blowing from the south or south-east, Singapore remains at continued risk of haze, said the NEA in a haze advisory on Sept 16.

But air quality could improve in the next two weeks, with the Meteorological Services forecasting on Sept 16 more showers here for the rest of September, as compared with the first half of the month.