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 18 May 2025: India 33.7 µg/m³, Chile 32.6 µg/m³ and Mexico 22.5 µg/m³.
- 1India209 cities33.7
- 2Chile47 cities32.6
- 3Mexico48 cities22.5
- 4South Korea140 cities14.5
- 5Hong Kong13 cities14.2
- 6Japan559 cities10.5
- 7Belgium26 cities10.3
- 8Hungary5 cities9.4
- 9New Zealand6 cities9.4
- 10Bosnia and Herzegovina5 cities9.3
- 11Poland57 cities9.0
- 12United Kingdom67 cities, was 58.7
- 13Malta4 cities8.5
- 14Latvia4 cities8.4
- 15Romania8 cities8.4
- 16Slovenia12 cities8.1
- 17Slovakia38 cities8.1
- 18The Netherlands33 cities7.8
- 19Austria32 cities6.9
- 20France29 cities, was 976.9
+ 15 more countries, 6.8 µg/m³ and below
- 26United States851 cities6.1
Not counted on this day, too few cities measured: Taiwan since 4 May 2025, Laos since 3 May 2025, Martinique since 3 May 2025 and 8 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.