Just days before the International Day of Clean Air for Blue Skies on September 7, Malaysia declared an emergency in Serian, Sarawak. Smoke from forest and peatland fires in Indonesia had pushed the district’s Air Pollution Index to 519, above Malaysia’s emergency threshold of 500. Schools closed, cloud-seeding operations began and communities across Borneo were reminded that polluted air does not stop at a national border.
The timing gives the seventh annual observance particular urgency in Southeast Asia. Under the 2026 theme “Clean Air for Climate Action,” the United Nations is calling for measures that simultaneously protect public health, strengthen economies and slow climate change.
Context: The Air Southeast Asia Shares
Air pollution across the region comes from overlapping sources. Vehicles and factories shape daily exposure in cities such as Jakarta, Bangkok, Hanoi and Manila, while coal-fired power generation adds fine particles and other pollutants. Agricultural burning, household waste, forest fires and drained peatlands can produce smoke that travels hundreds of kilometres.
Fine particulate matter, known as PM2.5, is especially dangerous because it can penetrate the lungs and enter the bloodstream. The World Health Organization estimates that the combined effects of outdoor and household air pollution are associated with 6.7 million premature deaths globally each year. Only 12 percent of cities worldwide currently record air-quality levels meeting WHO standards.
Cost: Dirty Air Carries a Human Price
The effects are visible in Greater Jakarta, where approximately 42 million people live across interconnected administrative areas. A 2026 study found that neighbouring Tangerang, Bogor, Depok and Bekasi contributed around 38 percent of Jakarta’s PM2.5 pollution. Industrial activities produced as much as 49 percent of the wider metropolitan total, while transportation and coal-fired power plants contributed 22 percent and 19 percent respectively.
Professor Puji Lestari of the Bandung Institute of Technology summarized the challenge clearly: “Since pollution knows no borders, our response must move beyond administrative boundaries.”
Between 2018 and 2023, every 15-microgram-per-cubic-metre increase in PM2.5 was associated with an estimated 18 percent rise in acute respiratory illness in Jakarta. In 2023 alone, national health-insurance claims in the capital reached Rp1.19 trillion for 12 diseases linked to air pollution.
Comparison: Regional Data Reveal a Shared Challenge
The 2025 World Air Quality Report shows substantial differences across Southeast Asia, but no reason for complacency. Indonesia recorded an annual average PM2.5 concentration of 30 micrograms per cubic metre, six times the WHO guideline of five. Vietnam registered 29.7, Thailand 17.8, Malaysia 16 and Singapore 11.9 micrograms per cubic metre.
These annual figures should not be confused with daily Air Quality Index readings, which can change rapidly with weather and emissions. Together, however, they show that even countries recording comparatively cleaner regional averages remain above the recommended health guideline.
Cooperation: ASEAN Has a Foundation for Action
ASEAN adopted its Agreement on Transboundary Haze Pollution in 2002, and every member state had ratified it by 2015. Its second regional roadmap, covering 2023 to 2030, contains nine strategies for preventing fires, improving monitoring and moving national PM2.5 standards closer to WHO targets.
Dr. Supat Wangwongwatana of Thailand’s Thammasat University has spent three decades working on air-quality management. His central message is direct: “Transboundary haze pollution requires a coordinated response.”
The agreement and roadmap provide essential structures, but recent conditions in Sarawak demonstrate the need for faster implementation. Governments require compatible monitoring systems, shared hotspot data, rapid emergency procedures and enforceable accountability for companies or individuals responsible for illegal burning.
Change: Clean Air Can Strengthen Cities and Economies
Southeast Asia already possesses many of the required solutions. Expanding reliable public transportation, adopting cleaner fuels, electrifying buses and motorcycles, phasing down coal and accelerating renewable energy would reduce urban emissions. Protecting peatlands, supporting fire-free farming and ending open waste burning would address pollution beyond city centres.
More air-quality monitors should also be installed in schools, neighbourhoods and industrial areas, with understandable real-time information made publicly available. Health protection must accompany emissions reduction, particularly for children, pregnant women, older people and outdoor workers.
Clean air is not an environmental ambition detached from daily life. It determines whether children can attend school, workers can earn safely and families can open their windows. September 7 should therefore mark more than an annual observance: it should renew Southeast Asia’s commitment to making blue skies a shared regional achievement.
