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 7 Sep 2025: Pakistan 29.7 µg/m³, Peru 28.3 µg/m³ and Chile 27.8 µg/m³.
- 1Pakistan11 cities29.7
- 2Peru5 cities28.3
- 3Chile48 cities27.8
- 4Ghana4 cities24.4
- 5India218 cities18.4
- 6Philippines3 cities16.2
- 7Romania10 cities12.3
- 8Mexico40 cities12.2
- 9Taiwan45 cities12.2
- 10Poland72 cities11.6
- 11Serbia39 cities11.5
- 12Thailand73 cities10.1
- 13Bosnia and Herzegovina5 cities9.4
- 14Hungary11 cities8.8
- 15Latvia4 cities8.8
- 16Slovakia42 cities8.3
- 17Malta4 cities8.1
- 18South Korea140 cities7.9
- 19New Zealand10 cities7.1
- 20United States857 cities7.1
+ 24 more countries, 7.0 µg/m³ and below
Not counted on this day, too few cities measured: Sweden since 7 Sep 2025, Czechia since 3 Sep 2025, Greece since 3 Sep 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.