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 17 Sep 2025: Pakistan 45.7 µg/m³, Peru 40.1 µg/m³ and Chile 26.8 µg/m³.
- 1Pakistan11 cities45.7
- 2Peru5 cities40.1
- 3Chile44 cities26.8
- 4Ghana4 cities24.6
- 5India225 cities23.7
- 6Philippines3 cities21.7
- 7Brazil42 cities15.3
- 8Thailand70 cities11.2
- 9Serbia37 cities10.7
- 10Taiwan45 cities9.7
- 11Mexico48 cities8.9
- 12Hungary10 cities, was 128.5
- 13Greece12 cities8.4
- 14Malta5 cities8.2
- 15Italy32 cities8.1
- 16South Korea141 cities8.0
- 17Japan556 cities7.9
- 18Poland74 cities7.7
- 19United States871 cities7.5
- 20Latvia4 cities7.4
+ 29 more countries, the next at 7.3 µg/m³
Not counted on this day, too few cities measured: Lithuania since 30 Aug 2025 and China since 7 Aug 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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.