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 25 Aug 2025: Pakistan 36.6 µg/m³, Chile 33.6 µg/m³ and Peru 24.8 µg/m³.
- 1Pakistan11 cities36.6
- 2Chile48 cities33.6
- 3Peru5 cities24.8
- 4Philippines3 cities23.6
- 5Ghana3 cities22.1
- 6India222 cities19.8
- 7New Zealand10 cities13.2
- 8Mexico39 cities12.7
- 9Italy27 cities, was 712.3
- 10Spain103 cities12.0
- 11Malta4 cities12.0
- 12South Korea140 cities11.5
- 13Brazil3 cities11.4
- 14Bosnia and Herzegovina4 cities10.5
- 15Japan566 cities10.4
- 16Greece8 cities10.2
- 17Slovakia41 cities9.8
- 18Switzerland11 cities9.5
- 19Czechia17 cities9.3
- 20Hungary12 cities, was 49.2
+ 25 more countries, 9.0 µg/m³ and below
- 25United States857 cities8.1
Not counted on this day, too few cities measured: Martinique since 22 Aug 2025, Serbia since 10 Jul 2025, Thailand since 10 Jul 2025 and Taiwan since 10 Jul 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.