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 4 May 2024: N'Djamena 199.0 µg/m³, Chiang Khong 156.4 µg/m³ and Ban Houakhoua 156.4 µg/m³.
- 1N'DjamenaChad199.0
- 2Chiang KhongThailand156.4
- 3Ban HouakhouaLaos156.4
- 4KathmanduNepal106.2
- 5Ubon RatchathaniThailand86.9
- 6PhayaoThailand86.4
- 7Chiang RaiThailand83.8
- 8Mae SaiThailand83.7
- 9DelhiIndia83.6
- 10Santa MaríaPeru81.9
- 11NanThailand77.6
- 12LampangThailand77.5
- 13Chiang MaiThailand73.2
- 14LahorePakistan69.7
- 15UttaraditThailand69.6
- 16DhakaBangladesh67.3
- 17NacimientoChile63.5
- 18OsornoChile63.2
- 19Puerto VarasChile62.0
- 20Bueng KanThailand60.0
+ 2,754 more cities, 60.0 µg/m³ and below
Not counted on this day, too few days measured: Beijing since 2 May 2024, Tlaquepaque since 29 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.