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 to4 Apr 2024 That day's board

The worst cities for PM2.5 over the 7 days to 4 Apr 2024: N'Djamena 201.0 µg/m³, Mae Sai 146.3 µg/m³ and Chiang Khong 122.8 µg/m³.

  1. 1N'DjamenaChad201.0
  2. 2Mae SaiThailand146.3
  3. 3Chiang KhongThailand122.8
  4. 4Ban HouakhouaLaos122.8
  5. 5PhayaoThailand100.3
  6. 6Chiang MaiThailand96.0
  7. 7NanThailand92.6
  8. 8LampangThailand88.5
  9. 9LamphunThailand85.9
  10. 10Tha BoThailand84.7
  11. 11VientianeLaos84.7
  12. 12Chiang RaiThailand81.3
  13. 13KathmanduNepal79.8
  14. 14UttaraditThailand77.1
  15. 15DhakaBangladesh71.2
  16. 16PhraeThailand70.7
  17. 17Mae SotThailand66.7
  18. 18SukhothaiThailand64.6
  19. 19Kamphaeng PhetThailand63.8
  20. 20LoeiThailand63.5

+ 2,544 more cities, 62.2 µg/m³ and below

Not counted on this day, too few days measured: Toluca since 29 Mar 2024, Tlaquepaque since 2 Mar 2024 and Lak Si since 17 Feb 2024.

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.