On the morning of October 22, the air over Singapore briefly breathed easy, as hourly fine-particle readings settled into the normal band across the island, a welcome contrast to the season's worst reading of 288 that had settled over the western districts eight days earlier. Yet the calm is provisional, the kind that arrives when the wind pauses rather than when the fires have gone quiet. Smoke from burning land in Kalimantan and Sumatra continues to drift across the strait, and the national environment agency warns that the slower-moving daily index may yet rise again, as it has done before
Singapore Haze Eases Overnight, but NEA Warns Unhealthy Air Could Return October 22
The day's clean readings are a pause rather than an all-clear.
Mark
The hourly numbers look great today. Why is NEA still warning about unhealthy air?
Mimi
Because there are two measures. PM2.5 is a snapshot of right now, and it's been normal islandwide since 1am. The PSI is a 24-hour rolling average, so it carries yesterday's air with it.
Mark
And the west still read 103 at noon.
Mimi
Right, just over the line into unhealthy. Everywhere else was good to moderate.
Luke
Worth saying the 101 to 160 range is a forecast. The reporting confirms the noon readings, not that the air will actually get that bad.
Mark
What's driving the forecast?
Mimi
Smoke from fires in Kalimantan, carried by east-southeasterly or south-easterly winds. NEA said smoke was seen near Singapore on October 21, and the south of Kalimantan is expected to stay dry.
Luke
Though showers are also forecast over Singapore and the region on the 22nd. The source doesn't say how much those might clear the air.
Mark
And after that?
Mimi
Smoke may keep drifting in on the 23rd. On the 24th the winds shift to blow toward the south-west, and dry weather over Sumatra could send its smoke this way.
Luke
Again, that's "may." NEA is describing a possibility based on wind and rainfall, and nothing here says how thick the haze would be.
Der Puls
- Hourly fine-particle readings fell to normal across the island, a sharp drop from the October 14 peak of 288 in the west.
- The 24-hour index in the west still sits at 103, just inside the unhealthy band, carrying the memory of a season-high of 230 on October 18.
- NEA's advisory warns that unhealthy air returns on October 22, with readings forecast between 101 and 160 as smoke drifts in.
- Winds shifting south-west on October 24 could carry Sumatran smoke toward the island, keeping residents watching the sky.
- Relief is real but fragile: the clean hourly numbers are a pause, not an all-clear.
On the morning of October 22, the air over Singapore briefly breathed easy, as hourly fine-particle readings settled into the normal band across the island, a welcome contrast to the season's worst reading of 288 that had settled over the western districts eight days earlier. Yet the calm is provisional, the kind that arrives when the wind pauses rather than when the fires have gone quiet. Smoke from burning land in Kalimantan and Sumatra continues to drift across the strait, and the national environment agency warns that the slower-moving daily index may yet rise again, as it has done before in this season's long and familiar cycle of smoke and clearing.
By noon on October 22, the hourly fine-particle readings across Singapore had settled into the normal range, with the highest reading in the west. It was a striking change from October 14, when western Singapore recorded 288, the highest hourly reading of this haze season. The air had cleared enough that, for a few hours, the island could breathe without worry.
The 24-hour Pollutant Standards Index tells a slower story. It is a rolling average, so it lingers long after the air has improved. At noon it stood at 103 in the west, just over the line into unhealthy air, and the season's worst reading of 230 on October 18 still hangs in the record.
The National Environment Agency is not ready to celebrate. Its advisory warns that unhealthy air is expected to return, with readings between 101 and 160, as smoke from fires in Kalimantan and Sumatra drifts toward Singapore under shifting winds. The winds of October 23 may keep pushing smoke in, and on October 24 they are expected to turn south-west, possibly bringing Sumatran smoke with them.
For most healthy people, the haze means irritated eyes, noses and throats. For those with asthma, chronic obstructive pulmonary disease or heart failure, it can mean far more. Today's clean readings offer a pause, and the days ahead will show whether the air holds or the smoke returns.
By noon on October 22, the hourly fine-particle readings across Singapore sat between 19 and 45 micrograms per cubic metre, and the highest of those figures was in the west. All of them fell in the "normal" band. Eight days earlier, on October 14, western Singapore had recorded 288, the highest hourly PM2.5 reading of this haze season.
The islandwide "normal" classification for PM2.5 had held since 1am. The scale works in bands: zero to 55 is normal, 56 to 150 means an elevated concentration of fine particles, 151 to 250 is high, and anything above 251 is very high. PM2.5 is the gauge of current conditions, which is why it moves quickly.
The 24-hour Pollutant Standards Index moves more slowly, because it is a rolling average of six key pollutants. At noon it stood in the "good to moderate" range, meaning zero to 100, in nearly every part of the island. The exception was the west, where it read 103, just inside the "unhealthy" band of 101 to 200. Above 200 is "very unhealthy." The season's worst 24-hour reading came at 10am on October 18, when the western region reached 230, well into that top band.
The health concerns are the familiar ones. For healthy people, short-term exposure to high levels of haze particles may irritate the eyes, nose and throat. The particles can also affect the heart and lungs, particularly in people with chronic conditions such as asthma, chronic obstructive pulmonary disease or heart failure.
The improvement may not last. In an advisory issued on the evening of October 21, the National Environment Agency said unhealthy air quality is expected on October 22, with PSI levels that may range from 101 to 160. That forecast sits alongside the morning's better readings rather than contradicting them: the PSI lags behind hourly conditions, and the smoke source has not gone away.
The agency said showers fell mainly over western Singapore on the afternoon of October 21, while smoke haze from Kalimantan was observed near Singapore. Smoke haze was also seen over Sumatra. Showers are forecast over Singapore and the surrounding region on October 22, but dry conditions are expected over the southern parts of Kalimantan. Under prevailing east-southeasterly or south-easterly winds, smoke from fires there may be carried toward Singapore.
The outlook for the following days is similar. On October 23, south-easterly or south-southeasterly winds may keep pushing smoke from regional fires toward the island. On October 24, the winds are expected to shift to blow toward the south-west. With dry conditions forecast over southern and central Sumatra, NEA said smoke from Sumatra may then drift toward Singapore.
So the day's clean hourly readings are a pause rather than an all-clear. The things to watch are whether the 24-hour PSI in the west climbs back above 100, and whether the wind shift on October 24 brings Sumatran smoke in.
Bemerkenswerte Zitate
Unhealthy air quality is expected on Oct 22, with PSI levels that may range from 101 to 160.— National Environment Agency advisory, evening of Oct 21
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