‘The physical toll is visceral’: How Indonesia’s fire haze affects millions - visual guide

An aerial view of wildfires burning in Sungai Putri, Ketapang regency, West Kalimantan province in Indonesia. Photograph: Willy Kurniawan/Reuters

For months, parts of Indonesia’s Borneo and Sumatra islands have been ablaze. The fires are sometimes lit illegally as a cheap way to clear land for plantations of oil palm, of which Indonesia is the world’s largest producer.

So prevalent is the technique that it even has a special term: slash and burn.