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 5 Sep 2025: Pakistan 33.9 µg/m³, Chile 33.3 µg/m³ and Peru 24.9 µg/m³.
- 1Pakistan11 cities33.9
- 2Chile48 cities33.3
- 3Peru6 cities24.9
- 4Ghana4 cities23.1
- 5India229 cities19.5
- 6Philippines3 cities19.1
- 7Mexico39 cities12.8
- 8Spain102 cities12.3
- 9Italy23 cities12.3
- 10Malta5 cities11.6
- 11Bosnia and Herzegovina4 cities10.9
- 12Slovakia42 cities10.9
- 13New Zealand10 cities10.7
- 14Japan558 cities10.4
- 15Greece9 cities10.1
- 16Hungary11 cities, was 410.1
- 17Brazil3 cities9.9
- 18Switzerland11 cities9.2
- 19South Korea140 cities9.2
- 20Poland65 cities9.1
+ 23 more countries, 9.1 µg/m³ and below
- 28United States868 cities7.3
Not counted on this day, too few cities measured: Lithuania since 5 Sep 2025, Luxembourg since 2 Sep 2025, Martinique since 22 Aug 2025 and 3 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.