The smoke is now too thick for Indonesia's own firefighting planes

Smoke that closes schools is one thing. Smoke too thick for the aircraft sent to put the fires out is another. Malaysia's foreign minister said this week that Indonesia has about 60,000 personnel working the fire lines, and that 34 planes and helicopters cannot fly because the air is too dirty to see through. Cloud seeding, the method of forcing rain out of a cloud, needs clouds with rain in them, and there are none. The fires on Sumatra and Borneo are Indonesia's most intense in 11 years, driven by an El Nino that forecasters expect to rank among the strongest in four decades.

On Saturday the cost crossed the border in a new form. Firefly, a low-cost airline owned by the same group as Malaysia Airlines, suspended its flights between Subang airport outside Kuala Lumpur and Seletar in Singapore because of low visibility, and kept them grounded through Wednesday. Al Jazeera reports that passengers are being moved onto Malaysia Airlines services between the two main international airports when seats are free. On Tuesday the air monitoring company IQAir ranked Singapore and Kuala Lumpur as the two most polluted cities in the world, at 199 and 183 on its index, where anything above 150 is treated as unhealthy. Singapore has brought back subsidised treatment for haze-related illness for the first time since 2015.

The part that will outlast this week is a rule. Foreign Minister Mohamad Hasan said he will ask ASEAN to treat haze as a natural disaster, which it currently is not. "We already have an ASEAN mechanism for natural disasters, but haze is not included or classified as a natural disaster," he said. The Philippines, which chairs ASEAN this year, has confirmed that haze is on the agenda when foreign ministers meet next month in Manila, before the bloc's annual summit.

Why it matters

Reclassifying haze would turn it from something neighbours complain about into something they can formally respond to, with relief teams, money and reporting that Jakarta would be expected to let in. If you live under the smoke, that may mean help arriving faster, and outside eyes on which districts and which companies keep burning. If you work or trade across the Malacca Strait, plan for more cancelled flights until the rain comes, because the airlines are now making that call on their own.