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 23 Mar 2025: India 42.0 µg/m³, Serbia 37.8 µg/m³ and Hungary 30.4 µg/m³.
- 1India228 cities, was 542.0
- 2Serbia39 cities37.8
- 3Hungary5 cities30.4
- 4Poland73 cities30.0
- 5Romania9 cities27.9
- 6Thailand84 cities27.2
- 7Laos3 cities26.9
- 8Bulgaria8 cities21.7
- 9South Korea141 cities20.7
- 10Slovakia41 cities19.4
- 11Latvia4 cities19.2
- 12Slovenia12 cities19.1
- 13Chile43 cities18.5
- 14Taiwan43 cities18.2
- 15Mexico10 cities17.6
- 16Hong Kong13 cities17.3
- 17Peru6 cities16.9
- 18United Kingdom7 cities16.6
- 19Switzerland3 cities, was 1015.8
- 20Germany229 cities15.8
+ 17 more countries, 14.7 µg/m³ and below
- 30United States837 cities6.6
Not counted on this day, too few cities measured: Portugal since 20 Mar 2025, Bosnia and Herzegovina since 18 Mar 2025, China since 14 Mar 2025 and 7 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.