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 25 Apr 2024: N'Djamena 197.1 µg/m³, Kathmandu 94.2 µg/m³ and Chiang Khong 78.9 µg/m³.
- 1N'DjamenaChad197.1
- 2KathmanduNepal94.2
- 3Chiang KhongThailand78.9
- 4Ban HouakhouaLaos78.9
- 5Ubon RatchathaniThailand77.7
- 6TlaquepaqueMexico77.7
- 7Santa MaríaPeru75.8
- 8NanThailand72.5
- 9Chiang MaiThailand71.6
- 10CoyhaiqueChile70.3
- 11PhayaoThailand69.4
- 12UttaraditThailand65.2
- 13LampangThailand65.1
- 14Mae SaiThailand64.1
- 15KalasinThailand64.0
- 16DhakaBangladesh63.5
- 17LamphunThailand57.6
- 18MukdahanThailand57.2
- 19Tha BoThailand56.9
- 20VientianeLaos56.9
+ 2,682 more cities, the next at 56.1 µg/m³
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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.