PSI enters unhealthy range with increase in Indonesian hotspots

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SINGAPORE - The air quality in Singapore entered the unhealthy range on Saturday (Oct 7) morning.

The 24-hour Pollutant Standards Index (PSI) readings ranged between 60 and 105 at 8am, with the highest recorded reading in the east.

A PSI reading of 101 to 200 is in the unhealthy range, for which the National Environment Agency (NEA) advises the public to cut down on outdoor activities.

In a statement on Friday night, NEA said that it will start to provide daily haze advisories from Saturday evening after the number of hot spots in Sumatra increased the likelihood of haze this weekend.

The agency said that 212 hot spots were detected on Friday, up from 65 on Thursday and 15 the day before.

Air quality worsened due to the change in wind direction on Friday afternoon that caused some of the lighter haze to blow towards Singapore, as satellite imagery showed smoke plumes and haze over southern and central Sumatra.

"There is a likelihood of haze affecting Singapore over the coming weekend if the fires persist and wind direction is unfavourable," said NEA.

The daily haze advisory can be used by the public to plan their activities and events for the next 24 hours, it said, adding that haze advisories have already been issued to several sectors including healthcare institutions, schools and workplaces.

In September 2019, and August 2016, PSI levels exceeded 100, and haze conditions in Singapore hit unhealthy levels.

The most severe haze conditions in Singapore were experienced in 2015, when the 24-hour PSI crossed 300 to hit the hazardous range on Sept 24. The Ministry of Education closed all primary and secondary schools the next day.

On Friday night, the one-hour PM2.5 in the central and eastern parts of Singapore were at elevated levels, meaning PM2.5 concentrations were above 55 micrograms per cubic m of air.

PM2.5 refers to fine particles - usually airborne - that are 2.5 microns or smaller and can be lodged deep in the lungs, posing severe health risks.

The PSI is computed based on a 24-hour average of concentration levels of PM2.5, among other pollutants.

With the air quality worsening, some in Singapore find their plans thwarted.

HomeTeamNS, in a Facebook post on Saturday morning, said that their annual Real Run 23 will have to be modified following the elevated haze situation.

It added that its 10km competitive race will be converted to a non-competitive run. Their other two race categories - the 5km non-competitive run and the 2.4km fun walk will remain.

"The safety of participants is our utmost priority, and we apologise for the inconvenience," it said.

ALSO READ: Hazy days ahead? PSI nears 100 on Saturday; NEA says it may increase if wind direction changes

This article was first published in The Straits Times. Permission required for reproduction.