Sarawak's official air quality table put two stations in its top band on Thursday evening. In the reading timed at 8.00pm on 3 September 2026, the Natural Resources and Environment Board recorded an Air Pollutant Index of 470 at Lubok Antu and 408 at the mobile station at IPD Serian, both in the band the Board labels "Very Hazardous". Lundu sat below them at 322, in the "Hazardous" band. Of the 20 stations on the table, 19 were above 100; only Miri, at 92, was not.

What the 8pm table actually showed

The Board publishes the index station by station, with the reading time on the page. At 8.00pm on 3 September, the figures ran:

  • 401 and above: Lubok Antu 470, IPD Serian 408
  • 301–400: Lundu 322
  • 201–300: Tebedu 284, Kuching 275, Sri Aman 269, Samarahan 263, Sarikei 214
  • 101–200: Betong 196, Kanowit 192, Sibu 181, Mukah 170, Bintulu 163, Samalaju 162, Lawas 156, ILP Miri 153, Limbang 152, Kapit 151, Bario 110
  • 51–100: Miri 92

Two of those are mobile units. The Board marks IPD Serian and Betong as MCAQM stations — Mobile Continuous Air Quality Monitoring — which is how it fills gaps in the fixed network. The spread matters as much as the peaks: the worst readings were in the southern interior near the Kalimantan border, while the northern coast around Miri was an order of magnitude cleaner on the same table.

Both of the highest readings sit in areas our division pages cover. Serian and Tebedu are in Serian division; Lundu and Kuching are in Kuching division.

What each band is supposed to mean

The Board prints its band table alongside the readings, with a health description for each step:

  • 0–50, Good: low pollution without any bad effect on health.
  • 51–100, Moderate: moderate pollution that does not pose any bad effect on health.
  • 101–200, Unhealthy: worsens the condition of high-risk people, meaning those with heart and lung complications.
  • 201–300, Very Unhealthy: worsens their condition further and lowers tolerance of physical exercise; affects public health.
  • 301–400, Hazardous: hazardous to high-risk people and to public health.
  • 401–500 and above 500, Very Hazardous: the same description as the band below it.

That last point is worth stating plainly, because it is a real limit of the scale. The Board's own table gives the same health wording to 320 as it gives to 470. The number keeps climbing past 400, but the published guidance stops distinguishing. A reader looking for what changes between "Hazardous" and "Very Hazardous" will not find it in the band table.

Why the figure lags what you can smell

The index is not a snapshot of the air at the moment it is published. The Board's note on the same page states that the API is calculated on a 24-hour running average of the most dominant parameter. A reading of 408 at 8.00pm therefore describes the day that ended at 8.00pm, not the hour.

The practical consequences run both ways. Smoke that arrives in the afternoon is diluted across the preceding 24 hours, so the index understates a sharp deterioration while it is happening. When the air clears, the same averaging holds the number up for the best part of a day afterwards. Neither is a fault in the measurement; it is what a running average does. It does mean that an index still in the 300s the morning after a clearance is not evidence that nothing has changed.

We run a separate air quality tracker on this site. It is a quick check and a trend rather than the official reading, and the Board's table is the number to use when it matters.

How one API figure is built out of five pollutants

The Department of Environment sets out the method nationally. Its explanation of the Air Pollutant Index describes the index as a way of reporting air quality in understood ranges instead of raw pollutant concentrations, and says the Malaysian system closely follows the Pollutant Standard Index developed by the United States Environmental Protection Agency.

The arithmetic is a selection, not a blend. The Department states that a sub-index is calculated for each of the five pollutants in the system, measured at varying averaging times drawn from World Health Organisation standards under the Malaysian Ambient Air Quality Standard. The highest of those five sub-indices becomes the API, and the pollutant responsible for it has to be reported alongside the figure, so that the relevant health category and the actions that follow from it are identified. The Department also notes that the bands correspond to action criteria set out in the National Haze Action Plan.

Who administers air quality in Sarawak

Two agencies are involved, and the division between them has been moving. The Board is a state body: its background page records that it was established on 1 February 1994 under the Natural Resources and Environment Ordinance, Chapter 84 of the Laws of Sarawak, pursuant to Section 3(1) of the 1993 amending Ordinance. Its remit has since been widened by the Natural Resources and Environment Ordinance 2024 and by the Environment (Reduction of Greenhouse Gases Emission) Ordinance 2023.

The Board also states that the transfer of autonomy over environmental matters under the Malaysia Agreement 1963 is expanding its statutory responsibilities into areas formerly held by the Department of Environment Malaysia, beginning with scheduled waste management.

Federally, the Department's air management remit runs under the Environmental Quality Act 1974 and its regulations, together with Malaysia's obligations under international agreements on air. The same remit lists open burning monitoring, hotspot tracking and peatland management alongside the monitoring station network and the API itself — the sources of the smoke and the measurement of it sitting within one division.

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