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 16 Sep 2025: Pakistan 36.2 µg/m³, Peru 29.6 µg/m³ and Chile 28.4 µg/m³.
- 1Pakistan11 cities36.2
- 2Peru6 cities29.6
- 3Chile47 cities28.4
- 4Ghana4 cities24.3
- 5India221 cities20.0
- 6Philippines3 cities18.4
- 7Mexico43 cities11.4
- 8Serbia29 cities11.3
- 9Thailand51 cities11.0
- 10Japan559 cities10.1
- 11Malta5 cities10.0
- 12Greece9 cities9.5
- 13Brazil3 cities9.4
- 14Romania11 cities9.3
- 15Taiwan41 cities9.3
- 16Bosnia and Herzegovina4 cities9.2
- 17Italy24 cities9.1
- 18South Korea140 cities9.1
- 19Spain118 cities8.9
- 20Poland71 cities8.9
+ 26 more countries, 8.7 µg/m³ and below
- 27United States865 cities6.7
Not counted on this day, too few cities measured: Czechia since 8 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.