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 to9 Apr 2026 That day's board

The worst cities for PM2.5 over the 7 days to 9 Apr 2026: Chiang Khong 159.2 µg/m³, Ban Houakhoua 159.2 µg/m³ and Mae Sai 144.0 µg/m³.

  1. 1Chiang KhongThailand159.2
  2. 2Ban HouakhouaLaos159.2
  3. 3Mae SaiThailand144.0
  4. 4VientianeLaos128.9
  5. 5Bueng KanThailand126.6
  6. 6PakxanLaos126.6
  7. 7Chiang RaiThailand123.5
  8. 8PhayaoThailand121.8
  9. 9LamphunThailand118.9
  10. 10NanThailand114.3
  11. 11LampangThailand104.9
  12. 12PhraeThailand98.7
  13. 13GurugramIndia94.5
  14. 14Chiang MaiThailand87.1
  15. 15ChangchunChina85.0
  16. 16LoniIndia81.5
  17. 17DispurIndia80.8
  18. 18GorakhpurIndia80.4
  19. 19Charkhi DādriIndia76.1
  20. 20LoeiThailand75.9

+ 3,068 more cities, 75.7 µg/m³ and below

Not counted on this day, too few days measured: Nagīna since 4 Apr 2026, Rahim Yar Khan since 26 Mar 2026, Kojomkul since 25 Mar 2026 and Tumkūr since 18 Feb 2026.

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.