Is the air quality good in Chiang Mai?
As of March 4, 2026, at 4:40 AM PT, Chiang Mai, Thailand is experiencing unhealthy air quality with an AQI exceeding 150, classified as "unhealthy," with PM2.5 as the dominant pollutant.
These conditions may increase the risk of respiratory issues, worsen heart problems, and impair lung function, particularly for children, the elderly, and people with underlying health conditions.
To stay safe during this temporary spike, limit time outdoors, seal windows, wear a mask when venturing outside, and use air purifiers indoors.
Air quality is dynamic and, like the weather, can change frequently. Chiang Mai ranked 3rd among the most polluted major cities in the world on Wednesday morning.
Click here for a real-time air quality map of Chiang Mai.
While today's conditions are poor, it is worth noting that Chiang Mai's average PM2.5 concentration in 2024 was 26.4 µg/m³, corresponding to a "moderate" AQI of 81 and 5.2 times the WHO annual guideline of 5 µg/m³.
Chiang Mai, Thailand, ranked as the 3rd most polluted major city globally, as of March 4, 2026, at 4:40 AM (PT). Source: IQAir.
When will air quality improve in Chiang Mai?
Air quality in Chiang Mai is expected to remain poor through the near term due to the ongoing burning season, which typically lasts from January through April and peaks in March (1).
Hourly air quality forecast for Chiang Mai, Thailand, as of March 4, 2026, at 4:40 AM (PT). Source: IQAir.
Over the past 30 days, air quality in the region was mostly in the moderate range, but recent conditions have rapidly deteriorated due to seasonal pollution events.
Daily air quality trends for Chiang Mai, Thailand over the past 30 days. Source: IQAir.
Conditions usually begin to improve later in April as weather patterns shift and the rainy season approaches. Rainfall and increased atmospheric mixing help disperse smoke particles and reduce concentrations of fine particulate matter in the air.
Until seasonal weather changes occur, pollution episodes may continue to occur intermittently during this period.
Air quality map of Chiang Mai, Thailand, as of March 4, 2026, at 4:40 AM (PT). Source: IQAir.
What is causing poor air quality in Chiang Mai?
The primary cause of poor air quality in Chiang Mai is biomass burning associated with agricultural practices and seasonal forest fires. These fires release large amounts of particulate matter, particularly PM2.5, into the atmosphere (2).
Major contributors to pollution include:
- Agricultural residue burning from rice, sugarcane, and maize crop fields.
- Forest fires during the dry season.
- Vehicle emissions and industrial pollution in urban areas.
- Smoke transported from neighboring countries in Southeast Asia.
Biomass burning releases pollutants including carbon monoxide, nitrogen oxides, and toxic particulate matter that contribute to haze and poor visibility.
Seasonal weather conditions also worsen the problem. Calm winds and temperature inversions during the dry season limit the dispersion of smoke, allowing pollution to accumulate near the ground and creating haze episodes across northern Thailand (3).
These combined factors make the northern region of Thailand particularly vulnerable to seasonal air pollution events during the early months of each year.
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How can I protect myself from poor air quality?
- Get a free air quality app for real-time air quality alerts and forecasts.
- Shut doors and windows and set the HVAC to recirculate mode.
- Contribute to your community’s outdoor air quality data.
- Stay indoors when air quality is poor; if you do need to go outdoors, wear a KN95/FFP2 mask.
- Run a high-performance air purifier to filter particles, gases, and other pollutants.
