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 to20 May 2024 That day's board

The worst cities for PM2.5 over the 30 days to 20 May 2024: N'Djamena 186.4 µg/m³, Coyhaique 105.6 µg/m³ and Santa María 93.1 µg/m³.

  1. 1N'DjamenaChad186.4
  2. 2CoyhaiqueChile105.6
  3. 3Santa MaríaPeru93.1
  4. 4LahorePakistan87.7
  5. 5Chiang KhongThailand85.3
  6. 6Ban HouakhouaLaos85.3
  7. 7NacimientoChile84.1
  8. 8DelhiIndia79.5
  9. 9KathmanduNepal77.6
  10. 10OsornoChile73.6
  11. 11HualpénChile72.0
  12. 12DhakaBangladesh67.8
  13. 13Puerto VarasChile66.2
  14. 14Ubon RatchathaniThailand62.6
  15. 15San CarlosChile60.1
  16. 16CuranilahueChile59.5
  17. 17PhayaoThailand57.2
  18. 18ChillánChile57.0
  19. 19NanThailand56.7
  20. 20Mae SaiThailand56.1

+ 2,772 more cities, 55.9 µg/m³ and below

Not counted on this day, too few days measured: Tlaquepaque since 18 May 2024 and 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.