Tuesday, 22 Oct 2019

Air quality inches towards unhealthy levels again, on second day of F1 weekend

SINGAPORE – The haze that lifted on Friday seems to be back on Saturday (Sept 21), the second day of the Formula 1 weekend.

Air quality deteriorated overnight as the 24-hour Pollutant Standards Index (PSI) inched towards the “unhealthy” range.

The 24-hour PSI reading was 91 to 97, within the moderate range, at 9am on Saturday.

It was up from a reading of 66 to 67 at 9pm the previous night.

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 32 to 45 micrograms per cubic m, within the normal band, at 9am.

This was a slight deterioration from the PM2.5 reading of 29 to 37, within the normal band, 12 hours earlier.

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.

At a media briefing on Friday, NEA said it expects the 24-hour PSI over the next day to range between the high end of the moderate range and the low end of the unhealthy range.

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

But in the coming days, the agency said dry weather is expected to persist over south Sumatra – the origin of most of the haze Singapore is experiencing.

If winds blow from that direction, the F1 race could take place under hazy skies and the PSI could creep into the middle of the unhealthy range.

However, the NEA said showers are expected in south Sumatra at the end of the month, and this could provide some respite.

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