Smoke from wildfires killed 3,560 people in Indonesia in September: report

The September the sky turned on 58 million people

On Thursday, the Centre for Research on Energy and Clean Air (CREA), a Helsinki-based think tank, released a study with a staggering headline figure: toxic smoke from months of forest and land fires across Indonesia killed an estimated 3,560 people in September alone. The figure is a modeled estimate of short-term mortality from fine particulate matter, PM2.5, small enough to lodge deep in the lungs. CREA said the September fire death toll was roughly double its August estimate of about 1,700, as El Niño-driven drought pushed the burning season to a ferocity not seen in years.

Adding 1,750 deaths from “chronic, non-fire emissions from urban and industrial air pollution sources,” CREA put September’s total air-pollution mortality at 5,310; up 42 percent from August’s 3,740. The number of Indonesians exposed to “unhealthy” to “hazardous” air quality reached a record 57.8 million in September, and in Kalimantan alone those inhaling hazardous-level air nearly tripled on the worst days, from 2.8 million to 6.4 million.

The geography of the deaths: Kalimantan, Sumatra, and Java’s different story

The deaths were not evenly spread. In Kalimantan, Indonesian Borneo, fire smoke accounted for between 94 and 99 percent of all air-pollution-related deaths; on Sumatra it was responsible for more than 80 percent. In Java, a different story: of 1,530 air-pollution deaths in September, 73–80 percent came from non-fire sources; industry, vehicles, waste burning.

The exposure data is extreme. In September, PM2.5 exposure breached the World Health Organization’s annual threshold by more than seven times nationally, ten times in Sumatra and 24 times in Kalimantan. In major cities of Central and West Kalimantan, average daily PM2.5 levels ran more than 20 times the WHO’s 24-hour guideline of 15 micrograms per cubic meter. Central Kalimantan had the highest risk: 14 deaths per 100,000 people; South and West Kalimantan, nine per 100,000. Wildfires burned more than 1.9 million hectares in the nine months to September, per deforestation monitor Nusantara Atlas, and health networks recorded more than 330,000 cases of acute respiratory infection countrywide. The health response has been running for weeks: Indonesia has been sending oxygen buses to aid residents choking on forest-fire haze.

What Jakarta will not say about the toll

The largest open question is whether Jakarta accepts CREA’s modeled toll at all. The National Disaster Mitigation Agency (BNPB) said on Thursday it would coordinate with other government bodies to review the report, spokesman Berton Panjaitan noting that modeled estimates “were different from figures recorded and individually verified by the government.” He did not say how many fire- and haze-related deaths the government itself has recorded. So the verified official count, the number Jakarta would defend, remains undisclosed.

Other gaps: CREA has not yet released October estimates, though BNPB data from Thursday showed 10,781 hectares of forest and land burning in the preceding 24 hours with 1,593 hotspots detected, meaning the toll is still accumulating. The true respiratory-disease burden beyond the 330,000 recorded infections is unknown, as is the effect of the coming wet season. And the report’s short-term mortality window, deaths within days of exposure, means the long-term chronic toll of this season’s exposure has not yet been counted at all.

El Niño’s ledger: when drought becomes a mass-casualty event

What makes September’s toll a story rather than a statistic is the mechanism: an El Niño weather pattern throttled rainfall across the archipelago, severe drought primed peatlands and forests, and months of fires converted climate variability into a mass-casualty public-health event; the same very strong El Niño that has southern Africa bracing for a harder 2027. Indonesia is enduring its worst fire season in more than a decade: roughly double August’s fire death toll in a single month, and a record 58 million people breathing air classified unhealthy to hazardous.

The same fires pushed toxic smog across Southeast Asia, raising pollution levels in Malaysia, Singapore, the Philippines and East Timor; a transboundary haze episode of the kind that has triggered diplomatic rows in past El Niño years. And it matters for the carbon ledger: nearly two million hectares burned in nine months, with the peatland component releasing carbon stored over millennia. For a country positioning itself as a climate player and asking the world to finance its energy transition, a fire season that kills an estimated 3,560 of its own citizens in a month is a credibility event as much as a health one.

Why a pollution report reads like a war dispatch

Through the 5D lens, September’s toll is what happens when a slow variable, drought, meets a fast one, fire, inside a governance system built for average years. The Indonesian state deployed more than 72,000 people for cloud-seeding and firefighting, activated over 2,100 doctors and health workers, and distributed 5.3 million masks; a huge mobilization that still left 58 million people breathing hazardous air. That gap between effort and outcome explains why Jakarta’s first instinct was to contest the modeling rather than the mortality.

Peatland and forest fires in Indonesia are not purely natural; decades of drainage for plantations and agriculture have made the landscape flammable, and El Niño merely lights the match. CREA’s split maps onto the country’s development geography: fire smoke dominates in Kalimantan and Sumatra, industry and traffic dominate in Java. The toll falls hardest on the provinces least equipped to absorb it; Central Kalimantan’s 14 deaths per 100,000 is a frontier-health-system number. The political temperature is rising at home too: students have marched in Jakarta over the fires, budgets and two years of Prabowo.

Historically, the pattern is cyclical: El Niño years bring fire years, fire years bring haze years, haze years bring diplomatic years. And the technological dimension is the modeling itself; short-term PM2.5 mortality estimates are standard epidemiology. A modeled death is still a death in the peer-reviewed literature; disputing the model rather than the mortality is usually disputing the politics, not the science.

The ripples: from Kalimantan’s clinics to Singapore’s skies

The second-order effects are already in motion. Indonesia’s health system is absorbing more than 330,000 recorded cases of acute respiratory infection, with 2,100 doctors and health workers activated in hard-hit areas; a surge load on provincial clinics that will persist into the chronic phase of this exposure. Regionally, the transboundary haze has reactivated the diplomacy of smoke: Malaysia, Singapore, the Philippines and East Timor are all downwind, and past El Niño fire seasons have produced formal complaints and pressure on ASEAN’s haze framework.

Economically, the season’s costs compound: firefighting and cloud-seeding mobilizations, lost agricultural output, health-system spending, and the carbon released from nearly two million burned hectares; peat carbon that undercuts Indonesia’s climate-finance pitch. And reputationally, the “avoidable” framing will follow Jakarta into every climate negotiation this year: a country asking the world to fund its transition cannot easily explain 3,560 of its own citizens dead from the sky.

What October’s numbers will decide

What happens next is dated. CREA has not yet released October estimates, but the inputs are grim: BNPB was still logging 1,593 hotspots and 10,781 burned hectares in a single 24-hour window at the end of the month, suggesting September’s record may not hold. The government’s promised review of the report, BNPB coordinating with other agencies, will produce either a methodological rebuttal or a quiet acceptance, and which one it is will signal how Jakarta intends to handle the politics of the toll.

Two clocks are running. The meteorological one: whether the El Niño drought breaks and the wet season arrives in time to end the burning. And the diplomatic one: whether downwind neighbors, Malaysia, Singapore, the Philippines, East Timor, escalate the transboundary haze into a formal grievance, as they have in past severe seasons. The question of who counts the dead, and what the count is allowed to mean, will burn longer than the fires.