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 17 Mar 2025: India 42.8 µg/m³, Serbia 40.9 µg/m³ and Bosnia and Herzegovina 34.1 µg/m³.
- 1India220 cities, was 542.8
- 2Serbia39 cities40.9
- 3Bosnia and Herzegovina4 cities34.1
- 4Poland73 cities32.4
- 5Romania9 cities31.1
- 6Thailand85 cities, was 1625.9
- 7Bulgaria8 cities23.5
- 8Laos3 cities22.9
- 9Slovenia12 cities21.8
- 10Hungary9 cities21.2
- 11Slovakia40 cities21.2
- 12Latvia4 cities20.9
- 13Switzerland3 cities, was 1020.8
- 14Hong Kong13 cities18.7
- 15Chile44 cities18.2
- 16South Korea141 cities18.2
- 17Taiwan43 cities17.6
- 18Austria36 cities17.5
- 19Peru6 cities16.9
- 20Germany230 cities16.7
+ 18 more countries, 16.4 µg/m³ and below
- 32United States834 cities6.7
Not counted on this day, too few cities measured: China since 14 Mar 2025, Malta since 13 Mar 2025, Pakistan since 13 Mar 2025 and 6 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.