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 27 Apr 2025: India 37.8 µg/m³, Chile 28.2 µg/m³ and Mexico 24.1 µg/m³.
- 1India223 cities37.8
- 2Chile47 cities28.2
- 3Mexico48 cities24.1
- 4Belgium27 cities15.1
- 5South Korea138 cities14.0
- 6Hong Kong12 cities12.7
- 7Hungary4 cities, was 1211.0
- 8Japan547 cities10.7
- 9The Netherlands36 cities10.4
- 10New Zealand6 cities10.2
- 11Poland65 cities10.0
- 12United Kingdom62 cities, was 59.4
- 13Romania7 cities9.0
- 14Malta5 cities8.8
- 15France49 cities8.4
- 16Slovakia36 cities8.2
- 17Germany241 cities6.9
- 18Slovenia12 cities6.8
- 19Lithuania4 cities6.5
- 20Latvia3 cities6.4
+ 12 more countries, 6.3 µg/m³ and below
- 22United States842 cities6.1
Not counted on this day, too few cities measured: Taiwan since 27 Apr 2025, Czechia since 26 Apr 2025, Laos since 26 Apr 2025 and 14 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.