// BBC WORLD NEWS — MONDO
Who's to blame for the toxic smog choking South East Asia?
Wildfires have been raging in Kalimantan, Indonesia for weeks
As Indonesia battles its worst wildfire season in a decade, a toxic smog is choking millions of residents in the region.
The air on the islands of Kalimantan and Sumatra have turned an ominous amber, with air quality recorded at hazardous levels.
The smog - also known as the haze - has also drifted beyond Indonesia's borders to neighbouring countries, raising public health concerns. It has obscured Singapore's skyline and forced some schools to close in Malaysia.
Now, anger is mounting at the companies accused of burning farmland - as well as the authorities who have struggled to stop them.
The annual dry season wildfires have been especially intense this year because of an unusually strong El Niño - a natural climate phenomenon which changes weather patterns around the world.
According to independent forest monitoring platform Nusantara Atlas, 1,043,377 wildfire hotspots have been recorded in Indonesia, burning a total of 900,000 hectares of land.
Many of these fires in Indonesia's forests and peatlands are caused by the razing of vegetation to clear land - a practice known as "slash and burn".
This is an agricultural method that has traditionally been employed by farmers in Indonesia to create nutrient-rich soil for new crops.
But today, many of these fires are associated with commercial farming and are taking place on a much larger scale - and are harder to control. Activists and government investigations have repeatedly accused some companies of using fire as a cheap way to clear large swathes of land.