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 24 Sep 2025: Pakistan 52.9 µg/m³, Peru 32.1 µg/m³ and India 24.4 µg/m³.
- 1Pakistan11 cities52.9
- 2Peru5 cities32.1
- 3India218 cities24.4
- 4Chile46 cities21.3
- 5Ghana4 cities18.2
- 6Philippines3 cities13.2
- 7Italy28 cities10.8
- 8Brazil3 cities10.3
- 9Mexico50 cities10.2
- 10Serbia39 cities9.3
- 11Thailand75 cities9.0
- 12Martinique3 cities8.8
- 13North Macedonia12 cities8.7
- 14Taiwan45 cities8.4
- 15Bosnia and Herzegovina5 cities8.3
- 16Hong Kong8 cities8.0
- 17Czechia23 cities, was 37.9
- 18Spain122 cities7.9
- 19Slovakia42 cities7.9
- 20Romania11 cities7.8
+ 31 more countries, 7.6 µg/m³ and below
- 25United States874 cities6.8
Not counted on this day, too few cities measured: 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 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.