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 22 May 2025: Chile 35.0 µg/m³, India 32.4 µg/m³ and Mexico 22.9 µg/m³.
- 1Chile47 cities35.0
- 2India205 cities32.4
- 3Mexico48 cities22.9
- 4South Korea140 cities14.6
- 5Hong Kong13 cities13.6
- 6Malta3 cities11.0
- 7Japan559 cities10.7
- 8New Zealand6 cities10.7
- 9Belgium26 cities10.1
- 10Bosnia and Herzegovina5 cities9.2
- 11Hungary5 cities9.2
- 12Poland57 cities9.1
- 13United Kingdom67 cities8.9
- 14Slovakia37 cities8.2
- 15Slovenia12 cities8.0
- 16Latvia4 cities7.8
- 17Romania6 cities7.8
- 18The Netherlands33 cities7.7
- 19France17 cities, was 977.4
- 20Italy6 cities7.0
+ 14 more countries, 6.9 µg/m³ and below
- 25United States841 cities5.8
Not counted on this day, too few cities measured: Estonia since 20 May 2025, Taiwan since 4 May 2025, Laos since 3 May 2025 and 9 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.