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 26 Sep 2025: Pakistan 43.8 µg/m³, Peru 35.8 µg/m³ and Chile 24.5 µg/m³.
- 1Pakistan11 cities43.8
- 2Peru5 cities35.8
- 3Chile47 cities24.5
- 4Ghana4 cities22.4
- 5India215 cities22.4
- 6Philippines3 cities16.5
- 7Mexico45 cities11.5
- 8Serbia38 cities10.8
- 9Thailand74 cities10.2
- 10Taiwan45 cities9.6
- 11Bosnia and Herzegovina5 cities9.4
- 12Poland72 cities9.2
- 13Italy27 cities9.1
- 14Romania11 cities9.1
- 15Brazil3 cities8.8
- 16Hungary10 cities8.8
- 17Greece6 cities8.5
- 18Japan557 cities8.4
- 19Malta5 cities8.1
- 20South Korea140 cities8.0
+ 27 more countries, 8.0 µg/m³ and below
- 24United States870 cities7.0
Not counted on this day, too few cities measured: Czechia since 18 Sep 2025, Lithuania since 5 Sep 2025 and Luxembourg since 2 Sep 2025.
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.