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 8 May 2025: Chile 34.4 µg/m³, India 31.5 µg/m³ and Mexico 21.9 µg/m³.
- 1Chile48 cities34.4
- 2India211 cities31.5
- 3Mexico47 cities21.9
- 4Hong Kong13 cities17.1
- 5South Korea140 cities12.5
- 6New Zealand4 cities10.0
- 7Hungary5 cities, was 128.8
- 8Japan554 cities7.7
- 9United Kingdom65 cities6.7
- 10The Netherlands22 cities6.2
- 11United States825 cities5.4
- 12Bulgaria5 cities5.2
- 13Australia22 cities4.2
- 14Canada110 cities4.2
- 15Lithuania3 cities4.1
- 16Norway20 cities3.7
- 17Iceland4 cities3.0
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.