The BBC’s Liza Tambunan is in central Kalimantan, as Indonesia is going through its worst wildfire season in a decade.

A poisonous haze has been choking hundreds of thousands of residents in the area, and has unfold to neighbouring nations such as Singapore and Malaysia.

So why has it been so unhealthy? Tambunan explains what peat is, and why peatland fires are so tough to comprise.