A record reading for the year
Singapore's one-hour PM2.5 reading reached 284 micrograms per cubic metre in the western part of the island on Wednesday, according to the National Environment Agency. It was the highest reading of the year and the first time during this haze period that the measure entered the agency's very high band.
PM2.5 particles are small enough to reach deep into the lungs. For comparison, Indonesia's wildfires in October 2015 pushed PM2.5 levels in western Singapore to a national record of 471 micrograms per cubic metre.
Schools close across the region
East Timor's government said it would suspend face-to-face learning for three days starting on 15 October, citing contamination by pollutant particles from wildfires in neighbouring regions or countries. The statement did not name Indonesia, but East Timor shares an island with part of Indonesia's East Nusa Tenggara province, where many fire hotspots have been reported.
Several states in Malaysia have also closed schools. The haze has drifted as far as the Philippines, and clinics in affected areas report a rise in respiratory complaints.
The worst season in 11 years
Indonesia is fighting its most intense wildfire season since 2015. Fires have burned through hundreds of thousands of hectares of forest and plantation land, according to authorities and monitoring groups.
Indonesian officials point to El Nino-linked dry conditions, which this year broke records months before the pattern was expected to peak. Experts also highlight slash-and-burn land clearing, a cheap way to open ground for planting that has changed the naturally fire-resistant landscape of Sumatra and Borneo.
Regional cooperation on the problem has never been simple. Governments in Southeast Asia have discussed a haze monitoring and compensation framework for years without fully putting one in place, and each bad season renews the argument over who should pay for the smoke. For now, the immediate work is firefighting, cloud seeding and public health warnings, while the dry weather lasts.