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 26 Jul 2025: Chile 45.5 µg/m³, Pakistan 35.5 µg/m³ and Peru 32.5 µg/m³.
- 1Chile47 cities45.5
- 2Pakistan11 cities35.5
- 3Peru6 cities32.5
- 4New Zealand10 cities24.0
- 5Ghana3 cities22.3
- 6India219 cities20.7
- 7Philippines3 cities17.4
- 8Mexico47 cities12.1
- 9Greece9 cities11.8
- 10Finland15 cities11.7
- 11Hong Kong13 cities11.7
- 12South Korea128 cities11.2
- 13Martinique3 cities10.9
- 14Malta4 cities10.6
- 15Romania11 cities10.6
- 16Bosnia and Herzegovina5 cities10.1
- 17Norway19 cities10.1
- 18Slovakia41 cities9.9
- 19Sweden17 cities9.6
- 20Poland59 cities9.0
+ 22 more countries, 8.7 µg/m³ and below
- 28United States844 cities7.7
Not counted on this day, too few cities measured: Lithuania since 25 Jul 2025, Ireland since 23 Jul 2025, Iceland since 22 Jul 2025 and 4 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.