Indonesia’s Health Ministry says acute respiratory infections tied to this year’s forest and peatland fires more than doubled in just over a week in early September, then kept climbing towards roughly 175,000 cumulative cases by late September. Here is what official data shows, why numbers moved quickly, and who needs to pay closest attention.
Key Takeaways
- Rapid rise in cases: Ministry data showed acute respiratory infection (ARI) cases more than doubled in just over a week in early September, exceeding 113,000 cumulative cases with over 12.5 million people exposed to haze.
- Continued escalation: By 21 September, the cumulative total reached roughly 175,000 cases across 63 districts in six provinces, including 40,363 cases in children under five.
- Severe fire season: The 2026 wildfire season is Indonesia’s worst in 11 years, driven by a “super El Niño” drought across Sumatra and Kalimantan.
- Transboundary impact: Smoke haze has reached Malaysia and Singapore, triggering regional alerts from the ASEAN Specialised Meteorological Centre.
- Data interpretation: The Health Ministry cautions that situation report figures are not directly comparable due to shifting reporting periods and provincial coverage.
What the Numbers Show
Official situation reports and statements outline the following timeline:
The Ministry notes that figures across updates should not be directly compared due to shifting parameters. The critical insight is the trajectory: smoke exposure turning into a rapidly growing public health burden.
Why Did Cases Surge?
Four primary factors explain the rapid increase in reported cases:
First, the fires are exceptionally severe. Driven by a “super El Niño” drought in Sumatra and Kalimantan, the 2026 season is the worst in 11 years. Dry peatland fires smoulder for weeks, producing thick, toxic smoke.
Second, satellite tracking shows smoke travelling vast distances, reaching Malaysia and Singapore and prompting ASEAN regional alerts.
Third, active fires spread across multiple regions beyond Sumatra and Kalimantan, including Papua, Java, and Sulawesi, exposing tens of millions of residents to smoke.
Fourth, regional frameworks such as the ASEAN Agreement on Transboundary Haze Pollution highlight the need for real-time health data sharing across borders to keep pace with the speed of physical smoke dispersion.
Vulnerable Groups
Children under five accounted for over 40,000 cases. World Health Organisation guidance notes that young children, older adults, pregnant women, outdoor workers, and people with chronic illness face the highest risk from fine particulate matter (PM2.5).
Health authorities advocate targeted messaging for specific groups: advising parents to limit children’s outdoor activity, encouraging vulnerable individuals to reduce exposure, and recommending workplace protections for outdoor labourers.
The Response Underway
International support included water-bombing helicopters from Japan and aerial firefighting support from Malaysia.
Practical Advice
Residents in affected countries should monitor local PM2.5, PSI, and API levels rather than relying on visual haze alone. For detailed guidance, see our guide on haze health effects.
Keep vulnerable family members indoors when air quality deteriorates, and seek prompt medical care for breathing difficulties or chest pain.
Frequently Asked Questions
How many infection cases were recorded?
Why did cases double rapidly in September?
Severe drought from a “super El Niño” intensified wildfires, expanding smoke exposure to over 12.5 million people.
Which areas are most affected?
Sumatra and Kalimantan experienced the severe impacts, with fires also spreading into Papua, Java, and Sulawesi.
How many children were affected?
Over 40,000 cases (nearly 25%) were in children under five years old.
Does the haze affect other countries?
Yes, smoke reached Malaysia and Singapore, triggering regional weather alerts.
What precautions should families take?
Monitor official PM2.5 readings, limit outdoor activities for high-risk individuals, and seek medical care if severe symptoms develop.
The Bottom Line
The dramatic surge in acute respiratory infections highlights the compounding impacts of severe peatland fires, persistent cross-border smoke pollution, and expanded health reporting across affected regions. As extreme drought and fire conditions exacerbate public health risks locally and regionally, proactive monitoring of localised air quality metrics such as PM2.5, PSI, and API becomes essential to protect vulnerable populations. Moving beyond aggregate national case numbers towards timely, targeted exposure prevention remains critical to mitigating the immediate and long-term health burdens of the crisis.
Editorial Note
Case data is sourced from Indonesia’s Ministry of Health via Reuters, The Straits Times, Anadolu Agency, and The Jakarta Post (Sept 10–24, 2026). Figures may not be directly comparable across reports due to varying timeframes and coverage. This article is for informational purposes only and does not constitute medical advice; consult a healthcare professional for specific health concerns or severe symptoms.
Sources
Reuters. “Indonesian wildfires cause respiratory infections to double in a week, health ministry says.” Reuters, 2026. https://www.reuters.com/business/environment/indonesian-wildfires-cause-respiratory-infections-double-week-health-ministry-2026-09-10/
The Straits Times. “Wildfires cause respiratory infections to double in Indonesia.” The Straits Times, 2026. https://www.straitstimes.com/asia/se-asia/wildfires-cause-respiratory-infections-to-double-in-indonesia
Anadolu Agency. “Indonesia records 175,000 respiratory infections as wildfires rage.” Anadolu Agency, 2026. https://www.aa.com.tr/en/asia-pacific/indonesia-records-175-000-respiratory-infections-as-wildfires-rage/4066243
The Jakarta Post. “Respiratory problems climb past 170,000 cases in haze-hit Indonesia.” The Jakarta Post, 2026. https://www.thejakartapost.com/indonesia/2026/09/24/respiratory-problems-climb-past-170000-cases-in-indonesia
Health Development Policy Agency (BKPK), Indonesia Ministry of Health. “Forest and Land Fire in Indonesia: When the Smoke Comes, We Are Ready.” Health Development Policy Agency, 2026. https://www.badankebijakan.kemkes.go.id
World Health Organization. “Ambient (Outdoor) Air Pollution.” World Health Organization, 2024. https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health