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 14 May 2025: India 33.4 µg/m³, Chile 32.9 µg/m³ and Mexico 21.2 µg/m³.
- 1India200 cities33.4
- 2Chile47 cities32.9
- 3Mexico46 cities21.2
- 4Hong Kong13 cities16.5
- 5South Korea140 cities15.2
- 6Malta5 cities10.8
- 7Hungary4 cities10.7
- 8Japan549 cities10.4
- 9Poland56 cities10.0
- 10Bosnia and Herzegovina5 cities9.6
- 11Latvia4 cities9.4
- 12Belgium39 cities8.9
- 13Slovenia12 cities8.7
- 14Slovakia35 cities8.7
- 15New Zealand6 cities8.6
- 16Romania8 cities8.6
- 17Lithuania4 cities8.5
- 18United Kingdom65 cities, was 58.1
- 19The Netherlands34 cities8.1
- 20Italy14 cities7.4
+ 13 more countries, 7.2 µg/m³ and below
- 24United States851 cities6.1
Not counted on this day, too few cities measured: Austria since 5 May 2025, Taiwan since 4 May 2025, Laos since 3 May 2025 and 10 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.