Singapore's PSI Edges Toward Unhealthy Levels as Haze Returns

The National Environment Agency is closely monitoring air quality across Singapore after the 24-hour Pollutant Standards Index in central parts of the island climbed to 91 at 2pm and 92 at 3pm on Aug 24. That remains within the moderate range, but it is approaching the unhealthy band, which begins at a PSI of 101 and runs to 200.

NEA attributed the deterioration to an escalation in hot spot and smoke haze activity over the weekend, with dense smoke plumes detected mainly in Kalimantan and southern Sumatra, and some plumes also observed in Riau. Dry conditions are expected to persist during the week, and with prevailing winds blowing from the south or south-east, NEA said Singapore could experience occasional periods of haze.

At 3pm, the 1-hour PM2.5 concentration ranged from 37 to 59 micrograms per cubic metre, within the normal to elevated range. NEA advised the public to use its website, haze microsite and myENV app for real-time information, and to refer to the 1-hour PM2.5 levels and personal guide before planning immediate outdoor activities. Earlier health guidance from NEA also encouraged reducing outdoor exertion, staying hydrated and keeping medication accessible for people with chronic heart and lung conditions.

Why Regional Fires Are Pushing Singapore's Air Quality Lower

The Fires Behind the Haze

The smoke affecting Singapore is being carried from land and forest fires in Indonesia, chiefly in Kalimantan and southern Sumatra, with additional plumes in Riau. Because dry conditions are forecast to continue and winds are blowing from the south and south-east, Singapore's exposure is likely to remain sensitive to fire activity in those source regions for at least the rest of the week.

What the Readings Signal

The 24-hour PSI is a rolling average, so it can lag behind sudden changes in smoke density. The 1-hour PM2.5 reading is a more immediate indicator of current exposure. With central Singapore recording the highest PSI value in the afternoon and PM2.5 levels already in the elevated range, residents may notice haze even while the 24-hour PSI remains moderate. Regional health data from Malaysia, where asthma cases rose 259 per cent and upper respiratory tract infection cases rose 124 per cent in the latest epidemiological week, shows the broader health burden of such haze, though Singapore has not crossed the unhealthy threshold.

How Singapore Residents Should Respond to Hazy Conditions

  • Check the myENV app, haze microsite or NEA website before scheduling outdoor activities; as of 3pm on Aug 24, central Singapore had the highest 24-hour PSI reading at 92.
  • Use the 1-hour PM2.5 reading and NEA's personal guide for immediate outdoor decisions, especially when PM2.5 is elevated, and reduce strenuous outdoor exercise if haze is visible.
  • Drink water and limit prolonged outdoor exertion during hazy periods; NEA advises that reducing outdoor activity and physical exertion can reduce ill effects from haze exposure.
  • People with chronic heart or lung conditions should keep their medication readily available, and vulnerable groups such as the elderly, pregnant women and children should seek medical attention promptly if they develop symptoms or feel unwell.