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 to9 Jan 2026 That day's board

The worst cities in Thailand for PM2.5 over the 30 days to 9 Jan 2026: Samut Sakhon 44.1 µg/m³, Nakhon Pathom 37.6 µg/m³ and Mueang Nonthaburi 35.0 µg/m³.

  1. 1Samut SakhonSamut Sakhon44.1
  2. 2Nakhon PathomNakhon Pathom37.6
  3. 3Mueang NonthaburiNonthaburi35.0
  4. 4Khlong Sam WaBangkok34.3
  5. 5Uthai ThaniUthai Thani33.1
  6. 6Ban Thai TanAng Thong33.0
  7. 7Khan Na YaoBangkok32.7
  8. 8Bang PakongChachoengsao32.6
  9. 9Nong KhaemBangkok32.4
  10. 10RatchaburiRatchaburi32.0
  11. 11Sing BuriSing Buri31.3
  12. 12PhetchaburiPhetchaburi31.2
  13. 13Bang NaBangkok31.0
  14. 14LamphunLamphun30.6
  15. 15Ban Samae DamBangkok30.0
  16. 16Phra PradaengSamut Prakan29.9
  17. 17Nakhon LuangPhra Nakhon Si Ayutthaya29.5
  18. 18Maha SarakhamMaha Sarakham29.2
  19. 19Bueng KumBangkok29.0
  20. 20Saphan SungBangkok29.0

+ 54 more cities, 28.8 µg/m³ and below

Not counted on this day, too few days measured: Sukhothai since 5 Jan 2026 and Khlong Luang since 2 Jan 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.