What Causes South East Asia's Haze

Forest fires in Indonesia have resulted in a smoky haze blanketing the South East Asian region for months.

Both the haze and the controversy around it have intensified in recent years. But what causes it?

Every year Indonesia sees agriculture fires in Riau province in East Sumatra, South Sumatra, and parts of Kalimantan on Indonesian Borneo.

The fires are said to be caused by corporations as well as small-scale farmers who use the slash-and-burn method to clear vegetation for palm oil, pulp and paper plantations.

The fires often spin out of control and spread into protected forested areas.

The problem has accelerated in recent years as more land has been cleared for expanding plantations for the lucrative palm oil trade.

The burnt land also becomes drier, which makes it more likely to catch fire the next time there are slash-and-burn clearings.

This year has seen one of the worst and most prolonged periods of haze, thanks to unusually dry weather in Indonesia caused by the El Nino climate phenomenon.