Haze in S'pore: Air quality hits unhealthy level again, could worsen on Formula 1 race day

Racing in slightly hazy conditions: Red Bull's Alex Albon in action during the third practice session of the Singapore Formula One Grand Prix on Sept 21, 2019. ST PHOTO: MARK CHEONG
A photo taken in Pasir Ris at around 3.45pm on Sept 21 shows slightly hazy conditions in the area. ST PHOTO: KEVIN LIM
A general view of southern Singapore at around 9.30am on Sept 21, 2019. ST PHOTO: JASON QUAH
The view from the Environment Building in Scotts Road on Sept 21, 2019, at around 9am. ST PHOTO: AUDREY TAN

SINGAPORE - The haze that lifted on Friday returned on Saturday (Sept 21), the second day of the Formula 1 weekend, and could get worse as smoke haze from the surrounding region is blown in.

In an update on Saturday evening, the National Environment Agency (NEA) said Singapore may experience increased haziness as winds are forecast to blow from the east or southeast. This could bring the 24-hour Pollutant Standards Index (PSI) readings over the next 24 hours into the mid-section of the unhealthy range on Sunday, the last day of the Singapore Grand Prix.

As of 11pm, PSI readings ranged from 96 to 109, within the moderate to unhealthy range, with the highest reading of 109 recorded in the southern part of Singapore.

A PSI reading of zero to 50 indicates good air quality while a reading of 51 to 100 is in the moderate range, and a reading of 101 to 200 is considered unhealthy.

The air quality is considered "very unhealthy" when the PSI ranges from 201 to 300, and "hazardous" when the PSI reading is more than 300.

Meanwhile, the 1-hour PM2.5 concentration, which the National Environment Agency (NEA) said is a better indicator of current air quality, was 43 to 56 micrograms per cubic m. This is between the normal and elevated band of the index.

The one-hour PM2.5 measures the average hourly concentration of PM2.5 particles - the dominant pollutant during haze episodes - and is meant to help people gauge immediate activities, such as whether they should go for a jog.

There are four bands on the PM2.5 concentration scale: 0 to 55 for normal, 56 to 150 for elevated, 151 to 250 for high, and very high for any higher readings.

The 1-hour PM2.5 readings are forecast to fluctuate between the normal and elevated bands.

NEA said 755 hot spots were detected in Sumatra on Saturday, an increase by 100 from Friday.

In the coming days, the agency said dry weather is expected to persist in the region.

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