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 7 days to 19 Mar 2025: India 36.3 µg/m³, Laos 26.6 µg/m³ and Thailand 23.2 µg/m³.
- 1India228 cities, was 536.3
- 2Laos3 cities26.6
- 3Thailand86 cities23.2
- 4Mexico54 cities, was 1421.8
- 5Chile46 cities20.7
- 6Serbia39 cities, was 1219.4
- 7Peru6 cities18.5
- 8South Korea141 cities18.4
- 9Lithuania4 cities17.5
- 10Taiwan44 cities17.0
- 11Poland71 cities16.4
- 12Hong Kong13 cities16.3
- 13Greece9 cities16.2
- 14Ireland6 cities12.3
- 15Romania10 cities11.5
- 16France106 cities, was 2311.3
- 17Latvia4 cities11.1
- 18Hungary7 cities10.4
- 19Germany236 cities9.9
- 20Switzerland10 cities9.6
+ 21 more countries, 9.6 µg/m³ and below
- 31United States837 cities6.8
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 18 Mar 2025, Luxembourg since 15 Mar 2025, Croatia since 14 Mar 2025 and 4 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.