This is no act of nature but a man-made catastrophe.
100,000 deaths and 500,000 sick is due to the outcome of illegal slash-and-burn activities in Indonesia in 2015. Some 125,000 fires had swept across the sprawling archipelago, pumping an estimated 1.75 billion metric tons of CO2 into the atmosphere.
The figures comes from a recent study conducted jointly by Harvard and Columbia universities in the US. Health expert Jonathan Buonocore, who studied the effect of air pollution on human health, told DW: "If we know, what the contribution of air pollution there is from the fires, and we know what the fires do to health we can then calculate what the health burden of the fires is."
Fine particulate matter PM10 and PM2.5 are particles smaller than 10 or 2.5 microns. The impact of particulates on the health of the millions of affected citizens is well researched. The tiny particles enter the lungs and cause respiratory problems such as asthma and, in some cases, even lung cancer. They can also result in heart attacks and brain strokes.
"Our study concluded that there were about 100,000 deaths due to the fires in the region in 2015. Out of them, 91,600 were in Indonesia, 6,500 in Malaysia and 2,200 in Singapore," Buonocore said.
According to World Bank data, almost a third of the 2.6 million hectares of land burnt in 2015 in Indonesia was of peatland. Peat is organic matter, which when dry is very flammable. Peat soils can be many meters thick. And only the upper layers of the peat are dry and typically about 20 centimeters below the surface the peat is quite humid. However, the fires spread underground through the root systems of trees that have been slashed or toppled. This dries out the surrounding peat, which ignites and the fires spread, ending up with slow-burning wet material and that produces heavy smoke. Peat fires are therefore hard to put out or control. David Gaveau of the Center for International Forestry Research (CIFOR), says: "When peat fires become large they can be put out only by rain. Peat fires are the ones that produce heavy smoke and cause a lot of problems both locally and across Southeast Asia."
Agricultural land is becoming scarce and therefore the less fertile peatlands are increasingly being brought under cultivation. There are various reasons behind the Indonesian government's inability to prevent the fires despite warnings. A major problem involves the ineffective enforcement of laws to prevent fires in provinces and islands. Local corruption certainly plays a big role. A team from the Ministry of Environment and Forestry on the island of Sumatra was attacked during this year's fire season by a mob, which threatened to burn them alive. The investigators were freed only after the government deployed heavily armed police.
The Indonesian authorities say they plan to stop granting new land concessions for palm oil plantations - one of the crops grown widely on cleared land.