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 7 days to 9 May 2025: Chile 34.5 µg/m³, India 30.8 µg/m³ and Mexico 21.7 µg/m³.
- 1Chile47 cities34.5
- 2India208 cities30.8
- 3Mexico47 cities21.7
- 4Hong Kong13 cities14.5
- 5South Korea140 cities12.5
- 6New Zealand4 cities9.5
- 7Hungary5 cities, was 129.1
- 8Japan554 cities8.0
- 9United Kingdom65 cities5.8
- 10Bulgaria5 cities5.6
- 11United States826 cities5.2
- 12The Netherlands22 cities4.6
- 13Australia22 cities4.3
- 14Canada110 cities3.8
- 15Lithuania3 cities3.8
- 16Norway20 cities3.7
- 17Iceland4 cities3.4
Not counted on this day, too few cities measured: Austria since 4 May 2025, Belgium since 4 May 2025, Switzerland since 4 May 2025 and 27 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.