Record wildfires in Indonesia trigger health crisis as haze spreads across South East Asia

High-intensity wildfires on Indonesia’s Borneo and Sumatra islands are worsening air quality and affecting neighbouring countries in South East Asia, including Malaysia, Singapore and the Philippines.

An independent estimate from the Nusantara Atlas portal says nearly 300,000 hectares of land have burned in Indonesia so far this year.

Official figures also point to a sharp rise in burned area. Indonesia’s forestry ministry recorded 202,000 hectares burned across the country from January to July, including 107,000 hectares in June alone.

A report in The Independent said wildfires destroyed nearly 95,000 hectares of land across Indonesia in July, almost doubling the damage recorded over the previous six months, as average temperatures for the month rose to their highest level in 35 years.

Indonesia’s fire season has been intensified by El Niño-linked dry conditions. In 2025, without the presence of El Niño, forest fires in Indonesia burned 359,000 hectares, according to Professor Bambang Hero Saharjo, a forest fire forensics expert at Institut Pertanian Bogor University, who spoke to the BBC.

Citing research reports, Bambang said that this year’s El Niño could burn an area as large as 11 million hectares, “putting it on par with one of Indonesia's worst wildfire seasons, which happened from 1997 to 1998,” the BBC quoted. 

Indonesia’s forestry minister Raja Juli said earlier this month that efforts to extinguish the fires were entering a crucial phase.

“Our problems are not over. September is the peak of El Niño,” he said. “September is the main fight for us.”

David Gaveau, founder of Nusantara Atlas, told news agency AFP that drier conditions had contributed to the spread of fires. But he said human activity also remained central. “El Niño does not ignite fires. It creates the dry conditions that allow human-started fires to escape and become very large,” he said.

Slash-and-burn land-clearing practices also contributed to the damage, Gaveau said. AFP reported that nearly 300,000 hectares had burned in Indonesia this year, based on Nusantara Atlas estimates.

Peat fires burn underground

Many of the fires are difficult to extinguish because they are burning on peatlands — wetland ecosystems made up of layers of partially decomposed organic material that become highly flammable when dry.

AFP reported that more than 210,000 hotspots were detected in peatland areas across Indonesia between January and August, citing the non-profit Pantau Gambut.

An article published by Science Daily said Indonesia’s dangerous peat fires are surging under severe drought and El Niño, raising fears that the country could be heading towards another devastating fire season like 2015.

“Tropical peatland fires rank among the most dangerous and stubborn fires on Earth,” it noted. Instead of spreading quickly through trees and vegetation, peat fires smoulder through dried wetland soils and large peat deposits, often continuing underground at relatively low temperatures. That makes them extremely difficult to extinguish and exceptionally polluting.

The article said the fires surged early in the 2026 fire season as an intensifying El Niño and severe drought dried wetlands that can burn underground for months.

These slow-smouldering fires are especially destructive because they release far more fine particles and several pollutants than typical tropical forest fires, while thick smoke can make them difficult for satellites to detect.

A study published in 2025 found that peat fires emit around three times more fine particulate matter than other tropical forest fires. They also generate higher levels of pollutants, including sulphur dioxide, organic carbon, methane and carbon monoxide.

Peat fires are a recurring problem in Indonesia, which contains about 36 per cent of the world’s tropical peatlands. During severe droughts, these landscapes dry out and burn, a pattern the country has repeatedly witnessed over the past three decades.

Indonesia reports wildfires every year, but its most destructive seasons have occurred during El Niño years, particularly in 1997 and 2015.

The current crisis has come as Indonesia experiences severe, widespread drought in the summer of 2026, similar to 2015.

Robert Field, a Columbia University researcher who developed the Global Fire Weather Database, said the strong El Niño was making the dry season drier over fire-prone parts of the country.

“The strong El Niño is making the dry season drier over the fire-prone parts of the country and exacerbating burning — just as we anticipated it would,” he said.

NASA said that, as of September 2, Indonesia’s 2026 fires had been burning for about a month and had released roughly 10 per cent as much emissions as the 2015 fires.

Fire Emissions Watch, a portal developed by the European Union’s Copernicus climate monitoring service, showed that Indonesia’s fire emissions from September 1 to 7 reached 19.7 million metric tonnes, making up more than one-third of the global total that week.

Respiratory cases rise

The wildfires have produced thick haze across parts of Indonesia after weeks of burning over large areas of Borneo and Sumatra.

Respiratory infections linked to hazardous wildfire pollution have more than doubled in just over a week, according to Indonesia’s health ministry.

A ministry spokesperson told reporters that, as of September 9, 113,336 people had been treated for respiratory conditions tied to the fires, up from 50,891 on September 1, news agency Reuters reported. More than 12.5 million people had been exposed to haze from fires across seven provinces, the ministry said.

Scientific American also reported that El Niño conditions were helping fuel wildfires across Indonesia, sickening around 100,000 people, and that more than 12.5 million had been exposed to haze caused by the fires.

Millions of people in South East Asia are being exposed to hazardous air pollution as haze from Indonesian wildfires crosses borders, disrupting schools and outdoor activity.

Deputy Health Minister Dante Saksono Harbuwono said in August that more than 5 million people across Borneo and Sumatra had been directly exposed to health risks from haze, while more than 1.4 million students had been forced to study remotely.

News agency Associated Press reported that worsening haze from forest and peatland fires had pushed air pollution to unhealthy levels in parts of Indonesia, adding to disruptions that had already affected more than 1.4 million students.

In Malaysia, the haze forced school closures in parts of Sarawak, while authorities declared an emergency last week in one town after air pollution breached emergency-level thresholds.

In the Philippines, haze drifting from Indonesia prompted health warnings and school disruptions, before air quality showed gradual improvement.

The haze also worsened air quality in Singapore’s central regions, according to data from the country’s National Environment Agency.