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 6 Sep 2025: Pakistan 30.0 µg/m³, Chile 29.2 µg/m³ and Peru 27.6 µg/m³.
- 1Pakistan11 cities30.0
- 2Chile48 cities29.2
- 3Peru5 cities27.6
- 4Ghana4 cities24.2
- 5India221 cities18.7
- 6Philippines3 cities15.9
- 7Taiwan45 cities13.0
- 8Poland72 cities12.0
- 9Romania11 cities11.7
- 10Mexico42 cities11.2
- 11Serbia39 cities10.6
- 12Thailand74 cities10.5
- 13Hungary11 cities9.2
- 14Bosnia and Herzegovina4 cities8.4
- 15South Korea140 cities8.3
- 16Slovakia42 cities8.2
- 17Latvia4 cities8.0
- 18Malta5 cities7.7
- 19Japan550 cities7.5
- 20Canada116 cities7.3
+ 25 more countries, 7.3 µg/m³ and below
- 22United States853 cities7.2
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.