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.
The worst cities for PM2.5 over the 7 days to 27 Apr 2024: N'Djamena 187.6 µg/m³, Kathmandu 103.8 µg/m³ and Santa María 83.0 µg/m³.
- 1N'DjamenaChad187.6
- 2KathmanduNepal103.8
- 3Santa MaríaPeru83.0
- 4Ubon RatchathaniThailand82.3
- 5TlaquepaqueMexico78.0
- 6Chiang KhongThailand75.4
- 7Ban HouakhouaLaos75.4
- 8CoyhaiqueChile71.6
- 9NanThailand69.4
- 10Chiang MaiThailand68.0
- 11DhakaBangladesh66.3
- 12BeijingChina65.2
- 13PhayaoThailand63.7
- 14UttaraditThailand63.4
- 15LampangThailand62.9
- 16Mae SaiThailand61.3
- 17KalasinThailand60.9
- 18MukdahanThailand58.0
- 19Bueng KanThailand57.0
- 20PakxanLaos57.0
+ 2,613 more cities, 56.8 µg/m³ and below
Not counted on this day, too few days measured: Lahore since 18 Apr 2024 and Toluca since 29 Mar 2024.
Cities counted each 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.