Indonesia/Singapore–– Look up. If it’s hard to see clearly, well, that is because the haze is back.
Forest fires in Sumatra over the past week have brought to Singapore’s northern areas a “moderate” PSI reading of 53 as of 4 p.m. Monday.
On the Pollutant Standards Index (PSI), an air-quality measurement, a reading of zero to 50 is “good.” Anything above 100 is considered “unhealthy.”
The poorer air quality was noted only in the northern part of Singapore however.
Other areas of the island recorded readings of between 33 and 41.
Responding to media queries on Monday, the National Environment Agency (NEA) attributed the hazy conditions to southwest winds that carried smoke from Sumatra, where forest fires have raged for the past week.
But it did not explain why air quality in the north which includes Kranji, Woodlands, Sembawang, Yishun, Seletar and Punggol was worse than elsewhere.
Besides the PSI, another air-quality scale, the PM2.5 that measures fine pollutants, was also higher in the north.
Because such fine particles are more dangerous they can enter the lungs or bloodstream more easily than larger dust particles the NEA cautioned those who were more vulnerable to avoid prolonged or heavy exertion.
These may include people with lung or heart disease, children and the elderly.
All over the island, residents have been noticing hazier skies this past week.
Alexandra Romualdez, 23, a teacher at an international school in Woodlands, said it was so hazy Monday morning that she could barely make out the landscape from the MRT train as it passed through Kranji.
“Just last week it hadn’t been that bad,” she said. “But I have noticed it getting worse recently.”
Sengkang resident Rachel Ang, 26, who is asthmatic, said that because of the haze, she has avoided going outdoors to exercise in case it triggers an attack.
The avid runner said she ended up going to the gym instead.
The NEA did not say how long the haze would last, but said that the southwest monsoon season, which typically lasts from June to September or early October, is the traditional dry season for the southern Asean region which includes Singapore and Indonesia.
It said that a rise in forest fires at this time could lead to “transboundary” smoke haze which means that smoke from other countries could reach Singapore.
The NEA added that the severity of such haze would depend on a variety of factors, including wind strength, rain, and how close or large the fires were.
Earlier this month, haze from hot spots in Sumatra had also affected Peninsular Malaysia, with the air quality rated unhealthy in Perak and Selangor.
In Singapore, the last time air quality deteriorated to unhealthy PSI levels was in 2010. This was also caused by haze attributed to forest fires in Indonesia.
Last week, NEA changed its air-quality reporting to three times a day – at 8 a.m., noon and 4 p.m. up from once a day.
It also began reporting thrice-daily PM2.5 data. Before this, it reported these numbers only annually.
What Is the PSI?
There are five key pollutants in Singapore’s PSI: sulphur dioxide, nitrogen dioxide, ozone, carbon monoxide and particulate matter. They are used as indicators as they are relatively easy to measure and are correlated with a group of other airborne toxins.
Besides the PSI, the NEA also reports levels of pollutants known as PM2.5, or particles smaller than 2.5 microns in size. This is measured because the finer the particle, the more likely it is to penetrate the lungs and the more dangerous it is to human health.