According to Indonesia's national disaster agency, there were 328,724 hectares of land burnt this year from January to August alone.The burning usually peaks from July to October during Indonesia's dry season.Many farmers take advantage of the conditions to clear vegetation for palm oil, pulp and paper plantations using the slash-and-burn method.They often spin out of control and spread into protected forested areas.

Besides irritating the respiratory tract and the eyes, pollutants in the haze can cause serious long-term damage to health. Indonesia has long struggled to police the vast rural expanse in Sumatra and Kalimantan. The slash-and-burn technique employed by many in the region is arguably the easiest way for farmers to clear their land and helps them get rid of any disease that may have affected their crops.

But it's not just small-scale farmers at work here. The concern is many of these fires are started by big corporations that want to plant oil palm plantations. Indonesia is the world's biggest producer of palm oil and the demand for the commodity has been rising. This means there is need for extra land for palm oil plantations.

Greenpeace International has said some companies in Indonesia appeared "to operate outside the law for years with little sanction".

Indonesia haze: Why do forests keep burning?