SmogRank / History / City race

Cities in Thailand, worst air first, day by day

Each measured city's average over the 30 days to every day since January 2023, worst first. Find your own city to follow it through the race, or keep to one country.

CountriesCities
The 30 days to12 May 2026 That day's board

The worst cities in Thailand for PM2.5 over the 30 days to 12 May 2026: Chiang Khong 75.3 µg/m³, Nan 68.3 µg/m³ and Phayao 63.3 µg/m³.

  1. 1Chiang KhongChiang Rai75.3
  2. 2NanNan68.3
  3. 3PhayaoPhayao63.3
  4. 4Mae SaiChiang Rai62.3
  5. 5SukhothaiSukhothai62.0
  6. 6Bueng KanBueng Kan54.3
  7. 7Chiang RaiChiang Rai52.2
  8. 8PhraePhrae49.3
  9. 9LamphunLamphun48.4
  10. 10Ubon RatchathaniUbon Ratchathani47.5
  11. 11UttaraditUttaradit44.0
  12. 12LoeiLoei43.7
  13. 13Uthai ThaniUthai Thani43.1
  14. 14PhichitPhichit41.8
  15. 15Chiang MaiChiang Mai41.7
  16. 16Suphan BuriSuphan Buri41.2
  17. 17Kamphaeng PhetKamphaeng Phet40.7
  18. 18Chai NatChai Nat38.5
  19. 19Ban Thai TanAng Thong34.0
  20. 20KanchanaburiKanchanaburi33.7

+ 60 more cities, 33.3 µg/m³ and below

Not counted on this day, too few days measured: Lampang since 10 May 2026, Mae Sot since 2 May 2026, Nakhon Sawan since 2 May 2026 and Khon Kaen since 26 Mar 2026.

30 days7 days
GoodModerateSensitive groupsUnhealthyVery unhealthyHazardousWHO 24-hour guideline, 15 µg/m³Fades where it stood: not counted that day

A city's number is its average over the 30 days, shown only when 21 of them were measured (5 of 7 on the 7-day race), the same minimum as the 30- and 7-day boards. A city whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air. Some large countries are thin or missing because their monitors' licences don't allow reuse. How we rank.

Not covered: the government monitoring networks of China and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.