Singapore's Use Of 24-Hour PSIDraws Criticism Amid Haze

As Singapore continues to experience hazy conditions, some netizens have questioned Singapore's use of the 24-hour Pollutant Standards Index (PSI) to communicate air quality, arguing that the reading may not provide the most immediate picture of conditions on the ground.

Some have called for greater attention to the one-hour PM2.5 readings, which reflect more recent air quality conditions.

Many netizens have criticised the 24-hour PSI reading as "useless", arguing that the one-hour PM2.5 reading provides a more accurate reflection of the current air quality.

NEA provides both measures for different purposes.

The 24-hour PSI is used to indicate the overall air quality over a 24-hour period, while the one-hour PM2.5 reading provides a more immediate indication of particulate levels.

The NEA has advised the public to check the one-hour PM2.5 readings and corresponding health advisories when planning outdoor activities.

For activities planned for the following day, it recommends referring to the 24-hour PSI forecast and accompanying health advisories...

The discussion comes as Singapore's air quality improved on Wednesday, 16 Sep 2026, with the 24-hour PSI returning to the moderate range across all five regions.

According to NEA, the 24-hour PSI ranged from 74 to 99 at 11am, with the highest reading recorded in the central region at 99.