Haze from Kalimantan fires pushes Sarawak air past 300 and cancels outdoor Merdeka events

Smoke from forest and peat fires in Indonesian Kalimantan pushed parts of Malaysian Sarawak into the hazardous band of the Air Pollutant Index on 1 September. Six stations read above 300. Earlier in the episode Serian had already hit 191, then 242. Kuching, Sri Aman, Lundu, Samarahan and Lubok Antu spent days in the unhealthy and very unhealthy bands.

This is the worst regional haze since 2015, when fires in Indonesia sent more than 500,000 people to clinics with respiratory illness. The 2026 season began in early August, eased briefly, then returned from 18 August as a second wave that also reached Brunei, Singapore, peninsular Malaysia and parts of Thailand and the Philippines.

The hotspot count

The ASEAN Specialised Meteorological Centre logged more than 7,200 hotspots in Kalimantan on 18 August, against 614 the week before. Prevailing winds carried the plume northwest across the island into Sarawak. Forestry Minister Raja Juli Antoni said on 1 September that smoke "has no identity card" and that wind direction, not borders, decides who chokes.

Indonesia's deputy health minister, Dante Saksono Harbuwono, said about 13,500 people were treated for respiratory infections in July and August. He put the number of people directly exposed on Borneo and Sumatra at about 5.5 million. Sarawak cancelled outdoor Independence Day events and prepared school-closure protocols. Masks and indoor lessons are already in use in the worst districts.

What governments are doing

Kuala Lumpur and Jakarta agreed on 24 August to intensify firefighting and to let Malaysia fly cloud-seeding sorties in Indonesian airspace along the border. Weather-modification flights are also planned on the Malaysian side. Indonesia says it is processing 30 cases and watching 52 forest-utilisation permit holders, with six already sanctioned.

The commercial pattern is old. Land is cleared for pulpwood and oil palm. Peat ignites. The dry season does the rest. 2024 and 2025 were quieter. 2026 is not. The Malaysian Consulate in Pontianak noted that Kalimantan had avoided a severe haze year in those two seasons and that this year broke the run.

Why the API number matters

Malaysia treats an API of 201 and above as very unhealthy and 301 and above as hazardous. Readings above 300 mean children, older people and anyone with asthma should stay inside. When six towns in one state sit in that band on the same day, the public-health load is no longer a forecast. It is a clinic queue.

Cloud seeding can knock particles out of a local column. It cannot put wet peat back under a concession that was drained for palms. Until those fires are out, Sarawak's air will follow the wind map from West Kalimantan. That is the part of the story that will still be true in a week if the hotspots stay in the thousands.