SmogRank / History / City race

Cities, 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 7 days to31 Mar 2023 That day's board

The worst cities for PM2.5 over the 7 days to 31 Mar 2023: Mae Sai 399.3 µg/m³, Chiang Rai 239.9 µg/m³ and Chiang Khong 232.0 µg/m³.

  1. 1Mae SaiThailand399.3
  2. 2Chiang RaiThailand239.9
  3. 3Chiang KhongThailand232.0
  4. 4Ban HouakhouaLaos232.0
  5. 5NanThailand138.2
  6. 6N'DjamenaChad132.6
  7. 7Chiang MaiThailand115.3
  8. 8LampangThailand109.4
  9. 9Bueng KanThailand108.1
  10. 10PakxanLaos108.1
  11. 11LamphunThailand95.0
  12. 12DhakaBangladesh92.2
  13. 13PhraeThailand86.4
  14. 14BamakoMali78.5
  15. 15LoeiThailand77.2
  16. 16LahorePakistan76.6
  17. 17TlaquepaqueMexico73.5
  18. 18KathmanduNepal65.4
  19. 19Kamphaeng PhetThailand62.5
  20. 20SukhothaiThailand59.9

+ 1,806 more cities, 57.8 µg/m³ and below

Not counted on this day, too few days measured: Phayao since 29 Mar 2023, Reykjavík since 27 Mar 2023, Kościan since 26 Mar 2023 and 17 more cities.

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.