Singapore Haze Today: PSI Hits Unhealthy Level Across All 5 Regions as Smoke From Indonesia Returns

Singapore’s air quality fell into the unhealthy category in all five regions on Tuesday, with the central region having the highest 24-hour Pollutant Standards Index (PSI) value at 154 due to the haze caused by fires in Indonesia.

The PSI was 128 in both the east and the west, 111 in the south and 104 in the north, as reported by the National Environment Agency (NEA) of Singapore, and a PSI reading between 101 and 200 is considered unhealthy.

The development was the first instance since September 2019 when all five regions of Singapore recorded air quality that was unhealthy at the same time; the northern region was the last to reach the threshold, hitting 102 around 1 a.m. after having registered 99 at midnight.

Smoke From Indonesia Drives Haze

The decline came after a number of days with moderate air quality and an increasing haze situation on Sept. 14.

The Meteorological Service of Singapore stated that smoke plumes from the fires in Kalimantan had moved towards the island, and haze was also visible over southern Sumatra. The agency attributed the smoke shifting towards the island to a change in the prevailing winds towards the east-southeast.

“With the prevailing winds forecast to continue blowing from the south-east to east-southeast, Singapore will likely be affected by smoke haze,” the NEA said in its Sept. 14 advisory.

The advisory states that dry conditions are expected over Singapore and the area surrounding it in the coming days, with the prevailing winds expected to stay between the southeast and east-southeast.

Singapore’s broader climate conditions have also been unusually dry. The Meteorological Service said in its August assessment that El Niño conditions were established in 2026 and expected to continue through the second half of the year. It also said models indicated a positive Indian Ocean Dipole was likely between August and December.

How the Haze Situation Developed

The present haze situation in Singapore started to get worse on Sept. 4, when the PSI level in the central area reached 101 in the morning. The NEA then started to publish daily updates on the haze.

On Sept. 13, the 24-hour PSI was between 68 and 82 at 5 p.m., the one-hour PM2.5 readings varying from 34 to 57 micrograms per cubic metre.

The agency cautions that ongoing fires in Kalimantan and in southern Sumatra, together with southeasterly or southerly winds, may still have an effect on Singapore.

On Sept. 14, at 5 p.m., the 24-hour PSI had increased to a range of 88 to 117, which caused the NEA to predict that the air quality would be high to moderate and then mid-unhealthy over the next 24 hours.

The Haze Task Force had already been put into action by the Singapore government in order to deal with the expected deterioration of the situation. It includes 28 public agencies, each of which has an action plan that can be put into effect when the PSI over 24 hours goes above 100 and enters the unhealthy category.

PM2.5 Levels Show Mixed Picture

On Tuesday morning, the one-hour PM2.5 readings showed a less uniform pattern.

In Singapore, the readings at 6 a.m. were between 32 and 44 micrograms per cubic metre, which is within the normal range; the central area had 66 micrograms per cubic metre and the western area 59, both of which are in the elevated range, due to the difference between the 24-hour PSI figure and the one-hour PM2.5 reading.

The PSI is employed for assessing air quality over the longer term and for issuing health advisories, whereas the one-hour PM2.5 reading gives more up-to-date information for people who are carrying out outdoor activities.

The NEA’s reported figures showed that although the 24-hour PSI values had slightly decreased by 9 a.m., they still fell within the unhealthy range.

Authorities Urge Residents to Limit Exposure

The NEA tells people to reduce their time spent outdoors when the PSI level over 24 hours is between 101 and 200.

Its haze advisory states, “The health impact of the haze is dependent on each individual’s health status, the PSI level, and the duration and intensity of outdoor activity. Reducing outdoor activities and physical exertion can help limit the ill effects from haze exposure.”

The Ministry of Manpower has also told employers to cut down on prolonged or strenuous outdoor work when the 24-hour PSI is between 101 and 200; its guidelines recommend measures including job rotation, taking sufficient indoor rest breaks, proper hydration and the postponement of non-essential outdoor work.

MOM’s guidelines are restrictive for vulnerable workers, including elderly and pregnant employees and those with chronic heart or lung conditions. Employers are advised to minimize or avoid prolonged or strenuous outdoor work for these groups when the PSI is in the unhealthy range.

NEA also clarified the circumstances in which N95 masks may be useful, “N95 masks are not required for short exposure, like commuting from home to school or work, or in an indoor environment. In general, a healthy individual who has to be outdoors for several hours may wear an N95 mask to reduce exposure when the forecasted air quality is in the Hazardous range (PSI >300).”

Smoke Haze May Persist Across Singapore

Singapore’s air quality is expected to remain vulnerable to further haze as dry conditions persist over Singapore and parts of southern Sumatra and Kalimantan. The Meteorological Service has stated that smoke haze will still have an impact on the island so long as the fires remain active and the winds continue to blow smoke towards Singapore.

People can keep up to date with the recent 24-hour PSI figure and one-hour PM2.5 readings by using Singapore’s official haze information sources, such as the NEA website, the govt website (haze.gov.sg) and the myENV app.