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 30 days to27 Apr 2024 That day's board

The worst cities for PM2.5 over the 30 days to 27 Apr 2024: N'Djamena 174.4 µg/m³, Kathmandu 102.8 µg/m³ and Chiang Khong 102.6 µg/m³.

  1. 1N'DjamenaChad174.4
  2. 2KathmanduNepal102.8
  3. 3Chiang KhongThailand102.6
  4. 4Ban HouakhouaLaos102.6
  5. 5Mae SaiThailand95.0
  6. 6Chiang MaiThailand80.7
  7. 7DhakaBangladesh80.7
  8. 8NanThailand74.2
  9. 9PhayaoThailand73.4
  10. 10LampangThailand70.4
  11. 11Ubon RatchathaniThailand68.4
  12. 12Tha BoThailand66.6
  13. 13VientianeLaos66.6
  14. 14LamphunThailand66.0
  15. 15Chiang RaiThailand65.1
  16. 16UttaraditThailand65.0
  17. 17KalasinThailand65.0
  18. 18MukdahanThailand59.8
  19. 19CoyhaiqueChile58.8
  20. 20PhraeThailand58.6

+ 2,581 more cities, 57.6 µg/m³ and below

Not counted on this day, too few days measured: Lahore since 22 Apr 2024, Pljevlja since 26 Mar 2024 and Tlaquepaque since 10 Mar 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.