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 11 Jun 2025: Chile 50.7 µg/m³, Peru 34.8 µg/m³ and India 30.3 µg/m³.
- 1Chile47 cities50.7
- 2Peru4 cities34.8
- 3India190 cities30.3
- 4Mexico44 cities19.8
- 5South Korea139 cities17.1
- 6Thailand78 cities12.8
- 7New Zealand6 cities12.7
- 8Serbia38 cities11.7
- 9Hong Kong13 cities11.1
- 10Japan568 cities10.7
- 11Malta3 cities9.8
- 12Taiwan45 cities9.8
- 13Canada112 cities9.7
- 14Latvia4 cities8.9
- 15Italy10 cities8.7
- 16Poland73 cities8.7
- 17Slovakia40 cities8.4
- 18Spain102 cities, was 1148.1
- 19Romania10 cities7.9
- 20Slovenia12 cities7.8
+ 18 more countries, 7.6 µg/m³ and below
- 25United States834 cities7.4
Not counted on this day, too few cities measured: Greece since 11 Jun 2025, Estonia since 10 Jun 2025, Laos since 8 Jun 2025 and 5 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.