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 7 Sep 2025: Pakistan 34.7 µg/m³, Chile 32.6 µg/m³ and Peru 25.0 µg/m³.
- 1Pakistan11 cities34.7
- 2Chile48 cities32.6
- 3Peru6 cities25.0
- 4Ghana4 cities22.3
- 5India226 cities19.4
- 6Philippines3 cities19.2
- 7Mexico37 cities12.3
- 8Italy23 cities12.0
- 9Spain100 cities11.9
- 10Malta5 cities11.6
- 11Bosnia and Herzegovina4 cities11.1
- 12Slovakia42 cities10.7
- 13Japan558 cities10.2
- 14New Zealand10 cities10.1
- 15Greece9 cities10.0
- 16Romania11 cities9.6
- 17Hungary11 cities, was 49.5
- 18Poland65 cities9.2
- 19Switzerland10 cities9.1
- 20Brazil3 cities9.0
+ 23 more countries, 9.0 µg/m³ and below
- 28United States868 cities7.1
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.