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 16 May 2025: India 33.9 µg/m³, Chile 32.9 µg/m³ and Mexico 21.9 µg/m³.
- 1India212 cities33.9
- 2Chile47 cities32.9
- 3Mexico47 cities21.9
- 4South Korea140 cities15.0
- 5Hong Kong13 cities14.8
- 6Japan561 cities10.9
- 7Hungary4 cities10.4
- 8New Zealand6 cities9.6
- 9Poland56 cities9.4
- 10Bosnia and Herzegovina5 cities9.1
- 11Belgium41 cities9.0
- 12Latvia4 cities8.9
- 13Malta5 cities8.9
- 14Romania8 cities8.4
- 15Slovenia12 cities8.4
- 16Slovakia40 cities8.4
- 17United Kingdom66 cities, was 58.3
- 18The Netherlands34 cities7.7
- 19Lithuania4 cities7.5
- 20Italy12 cities7.0
+ 13 more countries, 6.9 µg/m³ and below
- 23United States851 cities6.3
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.