Transboundary Air Quality Alert: Southeast Asia

Is the air quality good in Southeast Asia?

On August 28, 2026, air quality is poor across western Sarawak, much of western Peninsular Malaysia, West and Central Kalimantan, and parts of Sumatra, in part due to forest fire smoke and peatland burning.

Kuching, Malaysia on Borneo Island was the second most polluted major city in the world at 4:00 PM (local time), with AQI of 173, which falls within the "unhealthy" range.

These conditions can affect everyone, with children, older adults, pregnant people, and those with respiratory or cardiovascular conditions facing greater risks. Residents in affected areas should limit outdoor exertion, keep windows closed, wear a well-fitted mask outdoors, and run an air purifier indoors.

Southeast Asia accounts for five of the 20 most polluted major cities in the world this afternoon, with Kuching 2nd, Kuala Lumpur 3rd, Medan 12th, Singapore 16th, and Jakarta 17th.

For a more detailed look, see Kuching's air quality map.

Major cities ranking list showing Kuching, Malaysia as the 2nd most polluted city. Source: IQAir.

When will air quality improve in Southeast Asia?

Air quality in Kuching is expected to improve gradually over the coming days, while Kuala Lumpur’s air quality is forecast to reach the moderate range by tomorrow.

Hourly air quality forecast for Kuching, Malaysia, on August 28, 2026. Source: IQAir.

Hourly air quality forecast for Kuala Lumpur, Malaysia, on August 28, 2026. Source: IQAir.

The ASEAN Specialised Meteorological Centre raised its haze alert for the southern ASEAN region to Level 3 on August 26, warning that widespread moderate to dense smoke haze was emanating from clusters of hotspots in Kalimantan and that the hotspot and smoke haze situation could escalate further as dry conditions persist (1).

Below-normal rainfall is forecast across the southern part of the region through October, so fires and haze may continue into the coming weeks. Winds from the southeast and south are expected to keep carrying smoke from West Kalimantan northward into western Sarawak, while southwesterly flow can direct smoke from Sumatra toward Peninsular Malaysia and Singapore (2).

Indonesian authorities have expanded firefighting efforts, deploying aircraft and around 1,000 personnel across Kalimantan and Sumatra. Malaysia has also been permitted to conduct cloud seeding along the shared border. These measures may reduce smoke, but limited rain clouds could restrict cloud-seeding efforts, and haze may recur until sustained rainfall returns (3).

Air quality map of Southeast Asia, on August 28, 2026. Source: IQAir.

What is causing poor air quality in Southeast Asia?

Poor air quality across Southeast Asia is primarily driven by transboundary smoke from forest and peatland fires in Indonesia. Moderate to dense smoke over West Kalimantan and southern Sumatra is being carried by prevailing winds into Malaysia and Singapore (4).

A prolonged dry season, intensified by a strong El Niño phase, has dried vegetation and peatlands, making fires easier to ignite and spread. Most fires are linked to negligence or deliberate land clearing, with around 70 percent of Kalimantan’s hotspots located within industrial concessions (5). Authorities have arrested 72 suspected fire starters, investigated four companies, and imposed administrative sanctions on 14 others.

Limited rainfall is hindering firefighting efforts and allowing PM2.5 pollution to accumulate. Peatland fires are especially harmful because they can smolder underground for extended periods, producing persistent smoke that can penetrate deep into the lungs and enter the bloodstream (6).