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 12 Aug 2025: Pakistan 37.3 µg/m³, Chile 37.0 µg/m³ and Ghana 26.8 µg/m³.
- 1Pakistan11 cities37.3
- 2Chile48 cities37.0
- 3Ghana4 cities26.8
- 4Peru4 cities26.2
- 5India227 cities23.5
- 6Philippines3 cities21.7
- 7Italy28 cities16.0
- 8Bosnia and Herzegovina4 cities13.9
- 9Spain112 cities13.2
- 10Mexico40 cities13.0
- 11Switzerland11 cities12.1
- 12Brazil3 cities11.4
- 13Slovakia41 cities11.1
- 14South Korea140 cities11.0
- 15Czechia19 cities10.6
- 16Malta4 cities10.5
- 17Slovenia12 cities9.9
- 18Greece9 cities9.7
- 19Hungary12 cities, was 49.4
- 20Romania11 cities9.3
+ 25 more countries, 9.2 µg/m³ and below
- 31United States854 cities8.2
Not counted on this day, too few cities measured: Martinique since 9 Aug 2025, China since 7 Aug 2025, Serbia since 3 Jul 2025 and 2 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.