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 21 Jul 2025: Chile 53.3 µg/m³, Pakistan 37.1 µg/m³ and Peru 28.1 µg/m³.
- 1Chile48 cities53.3
- 2Pakistan11 cities37.1
- 3Peru5 cities28.1
- 4India202 cities21.2
- 5New Zealand10 cities14.4
- 6Mexico45 cities13.6
- 7Japan564 cities12.3
- 8South Korea140 cities12.0
- 9Italy23 cities11.5
- 10Martinique3 cities11.3
- 11Malta5 cities10.4
- 12Bosnia and Herzegovina5 cities10.2
- 13Slovakia41 cities10.1
- 14Spain114 cities, was 879.2
- 15Greece7 cities9.2
- 16Canada118 cities8.7
- 17Hungary11 cities, was 128.7
- 18Hong Kong13 cities8.4
- 19Romania11 cities8.4
- 20United States841 cities8.1
+ 21 more countries, 7.9 µg/m³ and below
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.