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 10 Aug 2025: Chile 41.4 µg/m³, Pakistan 33.8 µg/m³ and Peru 28.6 µg/m³.
- 1Chile48 cities41.4
- 2Pakistan11 cities33.8
- 3Peru5 cities28.6
- 4Ghana3 cities27.6
- 5India235 cities23.4
- 6Philippines3 cities22.2
- 7Brazil3 cities14.2
- 8Italy28 cities12.7
- 9Spain109 cities11.8
- 10Japan562 cities11.8
- 11New Zealand10 cities11.7
- 12Mexico40 cities11.3
- 13South Korea141 cities11.1
- 14Bosnia and Herzegovina5 cities10.4
- 15Hong Kong13 cities10.3
- 16Canada114 cities10.2
- 17Czechia17 cities10.1
- 18Greece8 cities10.1
- 19Slovakia41 cities10.0
- 20Romania11 cities9.6
+ 25 more countries, 9.1 µg/m³ and below
- 22United States855 cities8.8
Not counted on this day, too few cities measured: Martinique since 9 Aug 2025, China since 7 Aug 2025, Serbia since 3 Jul 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.