S’pore records highest PSI reading this haze season in central region as air quality worsens

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SINGAPORE – Hazy conditions worsened across Singapore on Oct 16, with the 24-hour Pollutant Standards Index (PSI) hitting a new high of 229 for this haze season at 3pm in the central region.

The east and west also recorded “very unhealthy” PSI levels for most of the day, while the hourly PM2.5 readings islandwide hovered in the “elevated” and “high” bands.

However, air quality improved later at night, with the one-hour PM2.5 readings – measured in micrograms per cubic metre and used as a gauge for current air quality – falling from the “high” band to “elevated” in all regions at 9pm.

The PM2.5 readings were 66 in the north, 117 in the south, 113 in the east, 125 in the west, and 136 in the central region at 9pm.

PM2.5 scores from 0 to 55 represent normal values, those between 56 and 150 indicate an elevated concentration of fine particles, while readings between 151 and 250 are considered high and scores above 251 are classified as very high.

The highest PM2.5 reading this haze season was recorded at 3pm on Oct 14 in the western part of the island at 288.

The PSI in central Singapore had earlier breached 229 at 3pm and remained at the same value at 4pm, marking a new high for this haze season.

At 9pm, the PSI reading for the central region remained “very unhealthy” at 219.

The other parts of Singapore recorded PSI readings in the “unhealthy” band at that time, with the north at 156, south at 181, east at 195 and west at 198.

Air quality is considered unhealthy when the PSI – a 24-hour rolling average of six key air pollutants – is in the range of 101 to 200, and very unhealthy when it is in the range of 201 to 300.

Singapore is in its 12th consecutive day of unhealthy air since Oct 5 – the longest continuous stretch of poor air quality the country has endured since the 2015 haze crisis. That year, bad air lasted 14 days from Sept 23 to Oct 7.

In its daily haze advisory on the evening of Oct 16, the National Environment Agency (NEA) said the PSI forecast for Oct 17 could be between 150 and 230, putting it in the range of “unhealthy” to “very unhealthy”.

Some showers are expected over Singapore and the surrounding region, including over parts of Kalimantan, on Oct 17.

“With the winds forecast to shift to blow from the south-east or south-south-east, the transport of smoke haze from Kalimantan to Singapore may be reduced. However, some smoke haze from Sumatra may drift towards Singapore,” the agency said.

Similarly, showers are also forecast over Singapore and parts of Kalimantan on Oct 18 and 19, it added.

It said that the winds are expected to gradually weaken and blow from the south-east or south, which could further decrease the movement of smoke haze from Kalimantan to Singapore.