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 7 Jul 2025: Chile 53.3 µg/m³, Pakistan 37.0 µg/m³ and Peru 31.6 µg/m³.
- 1Chile47 cities53.3
- 2Pakistan11 cities37.0
- 3Peru5 cities31.6
- 4Japan564 cities20.2
- 5India215 cities19.3
- 6Mexico48 cities14.7
- 7Bosnia and Herzegovina5 cities13.4
- 8New Zealand10 cities12.5
- 9South Korea140 cities12.4
- 10Slovakia41 cities12.0
- 11Malta4 cities11.1
- 12Italy21 cities, was 910.8
- 13Martinique3 cities10.5
- 14United States833 cities9.4
- 15Hungary10 cities9.2
- 16Hong Kong13 cities9.1
- 17Spain119 cities, was 998.9
- 18Romania11 cities8.8
- 19Slovenia12 cities8.8
- 20Switzerland10 cities, was 108.0
+ 21 more countries, 7.6 µg/m³ and below
Not counted on this day, too few cities measured: Greece since 7 Jul 2025, Czechia since 3 Jul 2025, Serbia since 3 Jul 2025 and 4 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.