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 30 days to 25 Apr 2024: N'Djamena 173.3 µg/m³, Chiang Khong 101.3 µg/m³ and Ban Houakhoua 101.3 µg/m³.
- 1N'DjamenaChad173.3
- 2Chiang KhongThailand101.3
- 3Ban HouakhouaLaos101.3
- 4KathmanduNepal98.7
- 5Mae SaiThailand97.6
- 6DhakaBangladesh83.3
- 7Chiang MaiThailand80.4
- 8PhayaoThailand74.3
- 9NanThailand73.6
- 10LampangThailand69.9
- 11LamphunThailand67.4
- 12Ubon RatchathaniThailand66.8
- 13Chiang RaiThailand65.8
- 14Tha BoThailand65.5
- 15VientianeLaos65.5
- 16KalasinThailand64.8
- 17UttaraditThailand64.4
- 18MukdahanThailand59.8
- 19PhraeThailand58.5
- 20CoyhaiqueChile58.2
+ 2,614 more cities, the next at 58.0 µg/m³
Not counted on this day, too few days measured: Lahore since 22 Apr 2024, Pljevlja since 26 Mar 2024 and Tlaquepaque since 10 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.