Causes
The 1997 Southeast Asian haze was caused mainly by slash and burn techniques adopted by farmers in Indonesia. Slash and burn has been extensively used for many years as the cheapest and easiest means to clear the lands for traditional agriculture. Fire is also used during the long fallow rotation of the so-called jungle rubber in Sumatra and Kalimantan to remove most of the biomass, including the woody parts before new plantations are re-established.
Fire may also be deliberately used as a weapon to claim property on the islands and provinces where land ownership is not clear, an action taken by both smallholders and large operators alike. After burning out its previous owner, the smallholder or large operator plants their own crops there, gaining de facto control over the disputed land.
During the fire season, dry fuels readily ignite and lead to large wild fires. These accidental fires may have the same underlying socio-economic and institutional problems. In cases like this, fire suppression can be very difficult and costly especially when they reach the highly flammable peat-swamp areas.
Read more about this topic: 1997 Southeast Asian Haze