Stagnant Skies in Southeast Asia

In early April 2026, much of mainland southeast Asia (sometimes referred to as Indochina) was blanketed in haze. Wildland fires and agricultural burning created hundreds of hotspots and copious amounts of smoke and smog, while weather patterns kept the fouled air from dispersing.

The image above shows thermal anomalies — mostly fires and recently burned hotspots — across Laos, Thailand, Vietnam, Cambodia, and Myanmar (Burma) on April 4, 2026. Data for the anomalies map and for the natural-color image below were gathered by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite.

Wildland fires and agricultural fires produce a mix of air pollutants, including aerosol particles, carbon monoxide, nitrogen oxides, and sulfur oxides. Those gases and particles can often turn into ground-level ozone and haze (or smog). Such pollutants reduces outdoor visibility and have both short- and long-term effects on human and animal health.

The map below, derived from data acquired by the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite, shows concentrations of carbon monoxide about 5500 meters (18,000 feet) above sea level on April 4. Note the particularly high levels over Laos and northern Vietnam. Carbon monoxide can persist in the atmosphere for as long as a month and can be transported long distances, playing a role in regional air pollution and climate.

The next map below shows estimates of the concentration of atmospheric particles — an aerosol index — as observed by the spectrometers in the Ozone Mapping and Profiling Suite (OMPS) on the NOAA-20 satellite. The aerosol index at the 380nm layer indicates the presence of ultraviolet-absorbing particles in the air such as desert dust, volcanic ash, and smoke particles in the atmosphere. It is related to both the thickness and height of the aerosol layer in the atmosphere.

News reports from multiple countries described extremely poor air quality in the region in late March and early April 2026. The rainy monsoon season has not yet arrived, so many areas are approaching their driest conditions of the year, leaving more fuel and better burning conditions for intentionally set (agricultural) and naturally or accidentally caused fires.

Related Reading

The Japan Times (2026, April 3) Blood clots and burning eyes as pollution chokes north Thailand

NASA Earth Observatory (2013, March 28) Fires in Southeast Asia 

Regional Fire Management Resource Center – South East Asia (2026, March 26) Thailand Battles Worsening Haze as Satellite Images Reveal Intense Regional Fire Activity