SINGAPORE: The 24-hour Pollutant Standards Index (PSI) in Singapore exceeded 101 on the Friday (Sept 4) morning, with air quality entering the unhealthy range.
At 10am, the 24-hour PSI in the central part of the island was 105, according to the National Environment Agency (NEA) website. It has since dropped to 104 at 11am.
It first hit 101 in central Singapore at 7am, before climbing further to 104 at 9am.
Air quality is considered unhealthy when the PSI is in the range of 101 to 200, during which NEA advises the public to cut down on outdoor activities.
The last time the PSI hit unhealthy levels due to haze was in October 2023.
This time around, the 24-hour PSI started inching towards the unhealthy range early on Sept 4.
At 1am, the PSI was between 70 and 90, within the moderate range, with the highest reading of 90 recorded in central Singapore. The PSI in that region hit 99 by 6am.
In a weather advisory on Sept 1, the Meteorological Service Singapore said Singapore may experience hazy conditions in the next two weeks as dry weather is set to continue in the surrounding region into the first fortnight of September, despite sporadic showers expected in the second week.
With the prevailing dry conditions, there has been an escalation in the hot spot and smoke haze situation in the surrounding region, it added. Dense smoke haze was observed over southern and central Sumatra and various parts of Kalimantan on most days from around Aug 21.
This follows weeks of forest and land fires in Sumatra and Kalimantan in Indonesia, fuelled by a super El Nino weather phenomenon.
How badly Singapore is affected depends on wind direction.
Malaysia is already badly affected by the haze, with air quality reaching unhealthy levels in several states, causing a spike in asthma cases. In Sarawak, one of the worst-hit states, the town of Serian recorded an Air Pollutant Index of 408 at 8pm on Sept 3, putting it in the very hazardous category, while four other areas in the state recorded very unhealthy readings.
In Singapore, efforts have intensified to raise awareness of the increased risk of haze and to guide the public on measures to safeguard their health, the nation’s Haze Task Force told The Straits Times on Aug 24.
Doctors have been reminded to advise vulnerable groups – including the elderly, pregnant women, children, and those with lung or heart disease – to take precautionary measures.
In schools, teachers will conduct visual checks on students’ well-being, and haze advisories have been sent to workplaces.
Haze and air quality are shown through two readings on NEA’s website: the 24-hour PSI and the one-hour PM2.5 readings. Both measures serve different functions.
During periods of haze, the 24-hour PSI forecast and corresponding health advisories should be used to plan outdoor activities for the next day, said the NEA website.
The one-hour PM2.5 should be referred to when deciding on immediate outdoor activities, for example, going for a jog.
The 24-hour PSI is computed based on the daily average concentration of six pollutants, including PM2.5, sulphur dioxide, carbon monoxide and ozone.
The calculations are done based on readings from the past 24 hours.
PM2.5 refers to micro-pollutants found in smoke haze from forest fires. These particles – 30 times smaller than the width of a strand of hair – can get lodged deep in the lungs and enter the bloodstream.
Air quality is considered good for PSI values of between 0 and 50, and moderate for PSI values of between 51 and 100.
For PM2.5, air quality is considered normal for readings between zero and 55 micrograms (mcg) per cubic m. - The Straits Times/ANN
