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 8 Sep 2025: Pakistan 33.1 µg/m³, Ghana 28.0 µg/m³ and Peru 26.8 µg/m³.
- 1Pakistan11 cities33.1
- 2Ghana3 cities28.0
- 3Peru5 cities26.8
- 4Chile48 cities25.8
- 5Philippines3 cities19.0
- 6India214 cities18.2
- 7Mexico41 cities13.3
- 8Romania11 cities12.5
- 9Serbia38 cities12.4
- 10Poland72 cities11.5
- 11Bosnia and Herzegovina5 cities10.9
- 12Taiwan45 cities10.7
- 13Thailand73 cities10.3
- 14Greece6 cities9.2
- 15Hungary11 cities9.0
- 16Latvia4 cities8.9
- 17South Korea139 cities8.7
- 18Slovakia42 cities8.6
- 19Finland15 cities7.9
- 20Bulgaria8 cities7.7
+ 24 more countries, 7.3 µg/m³ and below
- 24United States860 cities7.0
Not counted on this day, too few cities measured: Malta since 8 Sep 2025, Sweden since 7 Sep 2025, Czechia since 3 Sep 2025 and 3 more countries.
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.