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 5 Sep 2025: Pakistan 28.9 µg/m³, Chile 28.3 µg/m³ and Peru 25.1 µg/m³.
- 1Pakistan11 cities28.9
- 2Chile48 cities28.3
- 3Peru5 cities25.1
- 4Ghana4 cities23.8
- 5India216 cities18.9
- 6Philippines3 cities14.8
- 7Taiwan42 cities12.1
- 8Poland72 cities11.9
- 9Mexico41 cities11.4
- 10Romania11 cities11.4
- 11Serbia39 cities10.6
- 12Thailand75 cities10.5
- 13Hungary11 cities9.3
- 14Japan549 cities8.7
- 15Slovakia42 cities8.6
- 16Malta5 cities8.4
- 17South Korea140 cities8.1
- 18Latvia4 cities8.1
- 19New Zealand10 cities7.7
- 20Canada116 cities7.5
+ 25 more countries, 7.2 µg/m³ and below
- 22United States849 cities7.0
Not counted on this day, too few cities measured: Czechia since 3 Sep 2025, Greece since 3 Sep 2025, Lithuania since 30 Aug 2025 and 2 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.