Escalating environmental risks across northern Borneo, transboundary haze generated by uncontained forest and peatland fires in Indonesia’s West Kalimantan province has crossed the international border into Sarawak, East Malaysia, Eco Business reports. Driven by severe El Niño conditions, air quality metrics in the frontier state of Sarawak deteriorated to critical levels, forcing local authorities to suspend in-person learning across border districts.

The cross-border crisis follows a rapid surge in satellite-detected hotspots and burnt territory across Sumatra and Indonesian Borneo.

On August 12, 2026, air pollution index (API) readings in Sarawak’s Tebedu district breached 200, the statutory threshold for very unhealthy air quality. It triggers mandatory closures across six primary schools. According to real-time air quality metrics from IQAir, Kuching briefly ranked as the world's most polluted major city on August 11, with 11 monitoring stations across Sarawak recording unhealthy readings.

In Indonesia, the National Disaster Management Agency (BNPB) confirmed that West Kalimantan remains the hardest-hit province, accounting for over 28,680 hectares (70,870 acres) of officially recorded burnt land, representing more than half of the national total across priority fire provinces. NGO estimates from Madani Berkelanjutan place the burnt area in West Kalimantan alone even higher at 50,558 hectares (124,932 acres). Concurrently, satellite monitoring platform Nusantara Atlas / FireWatch detected over 154,000 fire hotspots across Indonesia as of August 11, marking a 60% increase from late July and surpassing levels recorded during the severe 2019 and 2023 fire seasons.

Joint task forces are to deploy water bombing and other fire-suppression measures to contain hotspots and protect air quality. This chain of events ultimately activates ASEAN transboundary haze mitigation protocols, underscoring the importance of cross-border coordination in managing regional environmental and public-health risks. Supplemental budget approvals authorised by the central government are necessary to support ground crews and emergency logistics in high-risk provinces like West Kalimantan and Riau.

Besides school closures, the haze reportedly has also affected Formula 1 Singapore Grand Prix’s preparation that will take place on October 9-11. The operational advisory follows a spike in peatland fire hotspots across Indonesia, prompting race organisers to activate contingency health protocols.