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 to2 May 2024 That day's board

The worst cities for PM2.5 over the 30 days to 2 May 2024: N'Djamena 175.9 µg/m³, Chiang Khong 112.5 µg/m³ and Ban Houakhoua 112.5 µg/m³.

  1. 1N'DjamenaChad175.9
  2. 2Chiang KhongThailand112.5
  3. 3Ban HouakhouaLaos112.5
  4. 4KathmanduNepal105.8
  5. 5Mae SaiThailand87.1
  6. 6DhakaBangladesh79.2
  7. 7Chiang MaiThailand78.4
  8. 8Ubon RatchathaniThailand75.7
  9. 9NanThailand74.4
  10. 10PhayaoThailand73.1
  11. 11LampangThailand69.4
  12. 12Santa MaríaPeru69.0
  13. 13Chiang RaiThailand66.0
  14. 14Tha BoThailand65.1
  15. 15VientianeLaos65.1
  16. 16KalasinThailand64.7
  17. 17UttaraditThailand64.3
  18. 18CoyhaiqueChile62.7
  19. 19LamphunThailand62.6
  20. 20MukdahanThailand60.3

+ 2,636 more cities, 57.8 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.