SINGAPORE — Air quality across Singapore remained in the unhealthy range on Thursday (Oct. 8), with haze blanketing the island and the 24-hour Pollutant Standards Index (PSI) reaching 161 in the western region early in the morning.
At 9am, the 24-hour PSI ranged from 113 in the north to 161 in the west, while the central and eastern regions recorded 145 and 125 respectively. The readings put all five regions within the unhealthy band.
The deterioration follows several days of worsening haze conditions, with smoke from fires in parts of Indonesia drifting towards Singapore under prevailing winds.
Western Singapore records highest PSI
The western region recorded the highest 24-hour PSI reading, reaching 162 between 4am and 6am before easing slightly to 161 by 9am.
At 6am, the other regional readings were 147 in central Singapore, 128 in the east, 120 in the south and 113 in the north.
Singapore’s PSI is considered unhealthy between 101 and 200. The index is calculated using a 24-hour rolling average of six pollutants and is primarily used to guide planning for outdoor activities.
The latest readings mark the first time during the current haze episode that air quality across all five regions has remained in the unhealthy range.
PM2.5 conditions vary across the island
While the 24-hour PSI remained elevated, the shorter-term 1-hour PM2.5 readings were less severe in several parts of Singapore.
At 9am, readings had returned to the normal band in the south, east and north, at 25, 42 and 37 micrograms per cubic metre respectively.
The central and western regions were still in the elevated band, with readings of 61 and 76 respectively.
The distinction is important because the two measurements serve different purposes.
The 24-hour PSI is useful for planning activities over the following day, while the 1-hour PM2.5 reading provides a more immediate indication of current air conditions and can fluctuate significantly throughout the day.
Haze linked to fires in Indonesia
Singapore’s National Environment Agency said smoke haze from southern and central Sumatra, as well as parts of Kalimantan, could continue drifting towards Singapore.
Moderate to dense smoke plumes were observed over parts of southern Sumatra, while hotspots were also detected in Kalimantan.
Dry conditions are expected to persist across parts of the region, increasing the risk of further smoke haze. Prevailing southeasterly to southerly winds are expected to continue carrying smoke towards Singapore.
The NEA has forecast the 24-hour PSI to remain in the unhealthy range, meaning the haze situation could persist rather than clear quickly.
Residents advised to reduce strenuous outdoor activity
The unhealthy readings have prompted renewed health advice from authorities.
For healthy people, the NEA recommends reducing prolonged or strenuous outdoor physical exertion when the 24-hour PSI is in the unhealthy range.
For children, elderly people and pregnant women, prolonged or strenuous outdoor activity should be minimised.
People with chronic heart or lung conditions are advised to avoid prolonged or strenuous outdoor physical exertion when the PSI is unhealthy.
For people deciding whether to exercise or spend time outdoors immediately, the NEA recommends checking the latest 1-hour PM2.5 reading rather than relying solely on the 24-hour PSI.
Singapore Grand Prix activities could be affected
The worsening haze comes just as Singapore prepares to host the Formula 1 Singapore Grand Prix this weekend.
The Federation Internationale de l’Automobile said on Thursday that the race itself was not expected to be affected, but some outdoor entertainment activities could face restrictions if the haze worsens.
Authorities are monitoring the air quality and contingency measures are in place to protect teams and participants.
The situation is particularly notable because Singapore experienced unhealthy haze during the 2019 Grand Prix. At the time, organisers had medical assistance available and provided N95 masks to people who needed them.
Haze season remains a regional concern
The current conditions highlight Singapore’s vulnerability to transboundary haze during prolonged periods of dry weather in neighbouring parts of Southeast Asia.
The NEA said the regional hotspot and haze situation was likely to remain elevated over the next few days, with continued dry conditions expected across parts of Sumatra and Borneo.
For now, residents are being advised to monitor official air-quality readings and adjust outdoor activities according to both the 24-hour PSI forecast and the latest 1-hour PM2.5 readings.
With haze affecting all five regions of Singapore, the immediate outlook will depend heavily on wind direction, rainfall and whether smoke from regional fires continues to drift towards the island.
