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 19 Sep 2025: Peru 37.0 µg/m³, Pakistan 36.8 µg/m³ and Chile 26.6 µg/m³.
- 1Peru5 cities37.0
- 2Pakistan11 cities36.8
- 3Chile48 cities26.6
- 4Ghana4 cities24.5
- 5India221 cities20.8
- 6Philippines3 cities18.2
- 7Mexico44 cities11.3
- 8Serbia36 cities10.8
- 9Thailand72 cities10.6
- 10Japan558 cities9.9
- 11Taiwan43 cities9.7
- 12Brazil3 cities9.6
- 13Malta5 cities9.3
- 14Romania11 cities9.1
- 15Poland72 cities9.0
- 16Italy26 cities8.9
- 17Hungary10 cities8.8
- 18Bosnia and Herzegovina4 cities8.7
- 19Greece8 cities8.6
- 20South Korea140 cities8.6
+ 26 more countries, 8.5 µg/m³ and below
- 25United States869 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.