SmogRank / World / Asia / Thailand / Chiang Rai
Most polluted cities in Chiang Rai, Thailand
2 measured cities, this year; 2 above the WHO annual guideline. Worst: Mae Sai at 36.8 µg/m³, #104 in the world.
Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.
Cities coloured by their PM2.5 over the last 24 hours. Fires, smoke and ash: Oct 5, the newest UTC day mapped.
- 1Mae Sai 24%
- 2Chiang Rai 16%
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Estimated: cities without a monitor
Chiang Rai cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.
| City | 7-day estimate |
|---|---|
| Mae Chan | ≈ 11 µg/m³ |
Bad-air episodes in Chiang Rai
- Northern Thailand and Laos, April 202612 to 19 April 2026, 8 days13 cities219 µg/m³peak, Chiang Khong
- Northern Thailand and Laos, March and April 202631 March to 6 April 2026, 7 days10 cities223 µg/m³peak, Chiang Khong
- Thailand and Laos, November and December 202530 November to 3 December 2025, 4 days23 cities64 µg/m³peak, Mueang Nonthaburi
- Northern Thailand and Laos, May 202417 May 2024, 1 day8 cities32 µg/m³peak, Chiang Rai
- Thailand and Laos, April and May 202428 April to 7 May 2024, 10 days47 cities237 µg/m³peak, Chiang Khong
- Northern Thailand and Laos, March 20246 to 7 March 2024, 2 days16 cities178 µg/m³peak, Lampang
Times when many cities around here had PM2.5 at twice their usual or more on the same days.
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SmogRank, most polluted cities in Chiang Rai, Thailand, PM2.5, this year to 6 Oct 2026, 23:00 UTC, smogrank.com/th/region/chiang-rai?w=year.
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Updated 2026-10-06 23:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.