Fires in Indonesia’s West Kalimantan province have sent haze across the border into Malaysia, where worsening air pollution has forced six schools in Sarawak state to switch to online classes.Indonesia is entering the peak of its fire season, with West Kalimantan accounting for more than half of the nearly 49,000 hectares (121,000 acres) burned across six priority provinces as of Aug. 9.The fires are also threatening biodiversity, including orangutan habitat and rehabilitation efforts in West Kalimantan, while a separate blaze has forced the closure of Bromo Tengger Semeru National Park on the island of Java.Authorities have deployed tens of thousands of personnel and dozens of aircraft to fight the fires, but environmental groups say funding cuts and the intensifying El Niño are raising concerns about Indonesia’s preparedness.

JAKARTA — Haze from fires in Indonesian Borneo has drifted across the border into the Malaysian portion of the island, pushing air pollution there to “very unhealthy levels” and causing school closures.

On Aug. 12, Sarawak’s Tebedu district, near the Indonesia-Malaysia border, recorded an air pollution index (API) exceeding 200, considered “very unhealthy,” prompting the government to close six schools and shift classes online.