Looking to find the least polluted cities in Thailand to get a break from air pollution? Smart Air analyzed 2025 air pollution data for dozens of Thailand cities to generate the ranking of the “10 Least Polluted Cities in Thailand”.
Scroll down for the full rundown of the least polluted cities in Thailand and their annual PM2.5 levels. and their annual PM2.5 levels. The annual average PM2.5 in micrograms (µg/m3) is also given. For reference, the WHO recommended annual limit is 5 micrograms.
Rankings: 10 Best Air Quality Cities in Thailand
The rankings for the least polluted cities in Thailand are based on PM2.5 air pollution data from 2025.
1. Trang (9.6 µg/m³)
2. Nakhon Si Thammarat (10.6 µg/m³)
3. Narathiwat (10.7 µg/m³)
4. Hat Yai (10.7 µg/m³)
5. Surat Thani (10.8 µg/m³)
6. Phuket (11.1 µg/m³)
7. Songkhla (11.5 µg/m³)
8. Sakon Nakhon (16.8 µg/m³)
9. Chiang Mai (17 µg/m³)
10. Suphan Buri (17.9 µg/m³)
Read More: The 10 Most Polluted Cities in Thailand 2025?
Analysis: Least Polluted Cities in Thailand
Thailand’s cleanest-performing cities in this dataset record PM2.5 levels ranging from 9.6 µg/m³ (Trang) to 17.9 µg/m³ (Suphan Buri). Most cities cluster tightly between 10–12 µg/m³, particularly southern cities such as Trang, Nakhon Si Thammarat, Narathiwat, Hat Yai, Surat Thani, Phuket, and Songkhla. This suggests relatively consistent and comparatively better air quality in southern coastal regions, likely influenced by sea breezes, lower heavy industry concentration, and better natural air circulation.
However, while these cities represent Thailand’s lowest PM2.5 levels, nearly all still exceed the World Health Organization’s annual guideline of 5 µg/m³. Only Trang, at 9.6 µg/m³, approaches the WHO interim target of 10 µg/m³. Northern cities such as Chiang Mai (17 µg/m³) appear at the higher end of this “clean” list, which aligns with seasonal burning and regional haze patterns that typically affect northern Thailand.
How Air Pollution Was Measured to Find the Least Polluted Cities in Thailand
The above rankings of the least polluted cities in Thailand were based on their annual PM2.5 pollution levels in 2025.
These small pollutants are under 2.5 micrograms in width and are considered to be one of the more dangerous pollutants due to their ability to enter deep into the lungs and bloodstream.
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Hello, could you clarify what is your source of data? Is it the official PM2.5 monitors, and if so just one monitor per city or did you use averages if there was more than one?