SmogRank / History / Country race
Countries, worst air first, day by day
Each country's typical measured city over the 30 days to every day since January 2023, worst first. Press Play to watch the order change, or drag the slider to any day.
The worst countries for PM2.5 over the 30 days to 11 Feb 2025: India 90.8 µg/m³, Pakistan 90.5 µg/m³ and Bosnia and Herzegovina 67.0 µg/m³.
- 1India5 cities90.8
- 2Pakistan4 cities90.5
- 3Bosnia and Herzegovina3 cities67.0
- 4Thailand16 cities49.9
- 5China4 cities39.6
- 6Serbia14 cities38.8
- 7Slovenia12 cities27.7
- 8Poland75 cities26.8
- 9Romania9 cities26.5
- 10Bulgaria5 cities26.2
- 11Hungary9 cities23.2
- 12South Korea141 cities22.3
- 13Slovakia42 cities21.6
- 14Hong Kong13 cities19.1
- 15Croatia3 cities19.0
- 16Chile46 cities18.5
- 17Belgium45 cities18.4
- 18The Netherlands23 cities18.0
- 19Austria36 cities17.9
- 20Switzerland9 cities17.0
+ 22 more countries, 16.9 µg/m³ and below
- 34United States818 cities7.3
Not counted on this day, too few cities measured: Luxembourg since 2 Feb 2025, Czechia since 18 Jan 2025, Singapore since 16 Jan 2025 and 2 more countries.
Countries counted each day
A country's number is its typical measured city: the median of its cities' means over the 30 days (a city needs 21 of them measured; 5 of 7 on the 7-day race), shown only with 3 such cities. A country whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air; "was" beside a city count marks a month after many cities joined or left. 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.