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 to21 May 2024 That day's board

The worst cities for PM2.5 over the 30 days to 21 May 2024: N'Djamena 189.8 µg/m³, Coyhaique 106.3 µg/m³ and Santa María 94.5 µg/m³.

  1. 1N'DjamenaChad189.8
  2. 2CoyhaiqueChile106.3
  3. 3Santa MaríaPeru94.5
  4. 4LahorePakistan87.4
  5. 5Chiang KhongThailand85.5
  6. 6Ban HouakhouaLaos85.5
  7. 7NacimientoChile84.8
  8. 8DelhiIndia81.6
  9. 9KathmanduNepal75.6
  10. 10OsornoChile73.9
  11. 11HualpénChile72.9
  12. 12TlaquepaqueMexico72.6
  13. 13DhakaBangladesh69.3
  14. 14Puerto VarasChile65.7
  15. 15Ubon RatchathaniThailand62.2
  16. 16San CarlosChile60.5
  17. 17CuranilahueChile59.6
  18. 18ChillánChile57.4
  19. 19VillarricaChile56.4
  20. 20Mae SaiThailand55.9

+ 2,774 more cities, 55.5 µg/m³ and below

Not counted on this day, too few days measured: Pljevlja since 26 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.