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 30 days to 28 Jul 2025: Chile 51.7 µg/m³, Pakistan 34.9 µg/m³ and Peru 28.3 µg/m³.
- 1Chile47 cities51.7
- 2Pakistan11 cities34.9
- 3Peru5 cities28.3
- 4India211 cities20.7
- 5New Zealand10 cities16.6
- 6Mexico46 cities13.5
- 7Japan563 cities12.5
- 8South Korea140 cities11.1
- 9Martinique3 cities10.8
- 10Malta4 cities10.7
- 11Hong Kong13 cities10.4
- 12Greece8 cities10.2
- 13Italy23 cities9.8
- 14Canada117 cities9.4
- 15Bosnia and Herzegovina5 cities9.2
- 16Romania11 cities9.2
- 17Slovakia41 cities9.2
- 18Spain102 cities, was 878.5
- 19Hungary11 cities, was 128.5
- 20Lithuania4 cities8.2
+ 21 more countries, 8.2 µg/m³ and below
- 21United States846 cities8.2
Not counted on this day, too few cities measured: Serbia since 10 Jul 2025, Thailand since 10 Jul 2025, Taiwan since 10 Jul 2025 and Laos since 8 Jun 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.