September saw the return of the dreaded haze in full forcethe worst it has been since 2015. Millions of people here in Singapore and other parts of Southeast Asia choked on toxic air and wondered if this would be a recurring event, a new normal to resign themselves to. On September 18, the Pollutant Standards Index (PSI) shot as high as 149 in the southern region of the island, with one-hour PM2.5 concentrations reaching up to 181 micrograms per cubic meter (µg/m3).
A PSI above 100 is generally seen as unhealthy while a PM2.5 concentration above 150µg/m3 is considered high, exceeding the World Health Organization’s (WHO’s) air quality guidelines for airborne particulate matter by more than 10 times the safe threshold. PM2.5 refers to a class of toxic particles with diameters of 2.5 micrometers (µm) or smallersmall enough to enter our lungs and bloodstream, with the ability to cause cardiovascular and respiratory problems, especially for individuals who are sensitive to fine particles.
Satellite imagery shows the source of the haze to be raging forest fires on the Indonesian islands of Sumatra and Kalimantan, the smoke from which is carried over to neighboring countries by winds. Palm oil cultivators, both small- and large-scale, and often hard to track, rely on fire as a quick means of clearing the land for their plantations. These blazes can spread quickly and unpredictably, and have led to a rising death toll in parts of Indonesia as locals struggle to contain the flames.
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