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 8 Sep 2025: Pakistan 35.5 µg/m³, Chile 31.6 µg/m³ and Peru 24.7 µg/m³.
- 1Pakistan11 cities35.5
- 2Chile48 cities31.6
- 3Peru6 cities24.7
- 4Ghana4 cities22.2
- 5India219 cities19.2
- 6Philippines3 cities18.8
- 7Mexico37 cities12.4
- 8Italy23 cities11.9
- 9Spain100 cities11.7
- 10Malta5 cities11.7
- 11Bosnia and Herzegovina4 cities11.1
- 12Slovakia42 cities10.5
- 13Japan558 cities10.3
- 14New Zealand10 cities10.2
- 15Greece10 cities9.9
- 16Hungary11 cities, was 49.6
- 17Romania11 cities9.5
- 18Poland65 cities9.3
- 19Switzerland10 cities8.9
- 20South Korea140 cities8.9
+ 22 more countries, 8.8 µg/m³ and below
- 28United States868 cities6.9
Not counted on this day, too few cities measured: Czechia since 8 Sep 2025, Lithuania since 5 Sep 2025, Luxembourg since 2 Sep 2025 and Martinique since 22 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 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.