Sumatra haze 2026: Palembang, Muaro Jambi and PALI had unhealthy air on all 35 days

The Sumatra haze of 2026 has lasted five weeks and is not over. Good Air counted the days with unhealthy air at 26 places in Sumatra with government monitors, from 15 September to 19 October 2026 (35 days). Palembang, Muaro Jambi and Penukal Abab Lematang Ilir (PALI) had a daily ISPU above 100, the Tidak Sehat (Unhealthy) level, on all 35 days. Twelve places, all in South Sumatra, Jambi and Riau, were above 100 on at least 30 days. Updated regional counts to 23 October are in our Indonesian-language reports on Riau and Indragiri Hilir and South Sumatra.

The air got worse, not better, over those five weeks. In the week of 13 to 19 October, PM2.5 was higher than in the week of 15 to 21 September at every one of the 25 places we could compare, and the median place went from 87 to 156 µg/m³. Jakarta, for comparison, did not have a single day above 100.

This is our own count from KLH (Ministry of Environment) and BMKG monitors.

Key findings

• Three places were unhealthy every day. Muaro Jambi (whose monitors include two in Jambi city), Palembang and PALI were above ISPU 100 on 35 of 35 days. Indragiri Hilir (33 of 33) and Ogan Ilir (28 of 28) were above 100 on every day their monitors reported.
• Very Unhealthy for weeks. Muaro Jambi had 28 days above ISPU 200, the Sangat Tidak Sehat (Very Unhealthy) level. Palembang and PALI had 27, Tebo 21. Ten places had at least 10 such days.
• The dirtiest air on average was in Palembang. Its mean PM2.5 over the 35 days was 264 µg/m³, followed by PALI (256), Tebo (228) and Muaro Jambi (209). Jakarta averaged 39 µg/m³.
• Unhealthy days rose from 62% to 84%. In the first week, 110 of 177 place-days were above ISPU 100. In the latest week, 152 of 181 were. Days above 200 rose from 23 to 82.
• On 19 October, 21 of the 26 places were still above 100. The worst day for the region was 15 October, when 23 of 26 were.
• The north and the west coast had far fewer bad days. Medan had 8, Asahan and Bengkulu none.

What the ISPU levels mean

ISPU (Indeks Standar Pencemar Udara) is Indonesia's official air quality index, set by the Ministry of Environment in Regulation No. 14 of 2020. It has five levels: Baik (Good, 0 to 50), Sedang (Moderate, 51 to 100), Tidak Sehat (Unhealthy, 101 to 200), Sangat Tidak Sehat (Very Unhealthy, 201 to 300) and Berbahaya (Hazardous, above 300). ISPU is defined on 24-hour averages, so a daily figure is the right way to read it. We explain the index in full in what is ISPU.

Every regency, ranked

The table ranks the 26 places by the number of days with a daily ISPU above 100, then by days above 200. "Days with data" is out of 35. Mean PM2.5 is the average of daily means, in micrograms per cubic metre (µg/m³). Each place links to its live English page and its Indonesian ISPU page.

Most of these regencies have a single monitor, so each figure describes one station, not a whole regency. Tanjung Jabung Timur's monitor published its ISPU every day but its PM2.5 on only 12, so we leave its mean blank. Two numbers stand out. Musi Banyuasin was Unhealthy on 33 days but never crossed 200: a long, steady haze rather than sharp peaks. Tebo was above 100 on 32 days, but on 21 of them it was above 200, and its mean PM2.5 of 228 µg/m³ is the third highest.

Padang, the capital of West Sumatra, is not ranked because its monitor reported on only 24 days. It was above 100 on 19 of them (ISPU Padang). Rokan Hilir in Riau reported on 26 days and was above 100 on 11 (ISPU Rokan Hilir).

Province by province

Jambi had the worst record. Its three monitored places were above ISPU 100 on 100 of 105 place-days. The province grouping is ours, based on where each monitor stands.

The peat fires behind these numbers are close to the worst-hit monitors. In Jambi, the environmental group Walhi Jambi's satellite analysis on 8 October put the burned area at 43,451 hectares, with Tanjung Jabung Timur (12,533 ha), Tebo (7,063 ha) and Muaro Jambi (4,618 ha) among the largest. Jambi province recorded 26,957 cases of ISPA (acute respiratory infection) in September, the most in Jambi city (Mongabay Indonesia, 15 October).

Further north the haze arrived later. All 8 of Medan's unhealthy days were in October, 6 of them between 13 and 18 October. Batam, across the strait from Singapore, had none in the first week and was above 100 on every day from 13 to 19 October.

The haze is not over

The haze eased in late September. Only 8 places were above 100 on 23, 24 and 25 September. It came back from the end of the month and has stayed. From 13 October onwards, at least 21 places were above 100 every day, and on 14 October 16 were above 200.

The first and latest weeks, side by side:

Palembang's weekly mean PM2.5 rose from 142 to 341 µg/m³, Kampar's from 87 to 270 and Tebo's from 151 to 303. The fires are still burning. On 19 October, BMKG reported 2,424 hotspots in Sumatra, 1,560 of them in South Sumatra and 345 in Jambi (Riaunews, 19 October). Satellite data from the ASEAN Specialised Meteorological Centre put Sumatra's hotspot tally at 8,766 by 13 October, up 155% since 27 August (The Star, 15 October).

For Kalimantan, where the smoke is even thicker, read our Kalimantan haze report. For how Sumatra compares with the rest of Asia on PM2.5, see Asia's most polluted cities in October 2026. That study ranks cities by average PM2.5 over 1 to 18 October; this one counts unhealthy days over five weeks. Live readings for the whole region are on the Southeast Asia haze tracker and kualitas udara Indonesia.

How we measured

• Data. Hourly readings that Good Air collects from KLH's national ISPU network and from BMKG's PM2.5 monitors. Monitors only: no satellite estimates, model output or low-cost sensors.
• Places. We used the place rows behind our city pages, which average every monitor assigned to a place. Three exceptions. Ogan Ilir's page also averages in a BMKG monitor in Palembang (Musi 2), so for Ogan Ilir we used its own KLH monitor only. Lahat's page averages the Lahat and Muara Enim monitors, which are in different regencies, so we list them separately. Muaro Jambi's page includes two monitors in Jambi city, and we say so in the table.
• Daily value. The average of the day's hourly ISPU readings. KLH publishes each reading on a 24-hour basis. For BMKG-only places (Batam, Bengkulu, Pesawaran, Kototabang) the ISPU is our own, calculated from PM2.5 with the official conversion table. A day counts only with at least 12 hourly readings, and a place only with at least 28 of the 35 days.
• Missing concentrations. Three single-monitor regencies had days when the monitor published an ISPU but not the concentrations we use. On those days we used the ministry's published ISPU: 23 days for Tanjung Jabung Timur, 4 for Indragiri Hilir and 3 for Aceh Tengah.
• Impossible values. The ISPU scale ends at 500, but the feed runs past it, and some hourly readings are sensor errors: 5,210 in Kampar on 11 October, 6,675 in Aceh Tengah on 15 October and 3,038 in Indragiri Hilir on 29 September. We never use a daily maximum. We capped each daily average at 500, which affected 27 place-days. Capping does not change any count above 100 or 200.
• Cross-check. We counted the days again from PM2.5 alone, using the ISPU breakpoints of 55.4 and 150.4 µg/m³. The counts match within one day everywhere except Aceh Besar, where PM2.5 gives 3 days above 100 instead of 10. Its ISPU was driven by PM10 and by short spikes, so treat Aceh Besar's figure with care. Indragiri Hilir and Tanjung Jabung Timur have fewer PM2.5 days to check against.
• Left out. Pangkalpinang and Nagan Raya, whose monitors repeated the same reading day after day, and five places with too few days: Padang, Rokan Hilir, Aceh Selatan, Bandar Lampung and Lampung Selatan.
• Period. 15 September to 19 October 2026, in days as stored in our archive (UTC).

We will update this count when the haze season ends.