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 27 Aug 2025: Chile 33.8 µg/m³, Pakistan 33.7 µg/m³ and Peru 24.4 µg/m³.
- 1Chile48 cities33.8
- 2Pakistan11 cities33.7
- 3Peru5 cities24.4
- 4Philippines3 cities23.0
- 5Ghana3 cities22.0
- 6India221 cities20.0
- 7Mexico39 cities12.9
- 8New Zealand10 cities12.6
- 9Italy27 cities, was 712.3
- 10Spain104 cities12.2
- 11Malta4 cities11.7
- 12South Korea140 cities11.3
- 13Brazil3 cities11.1
- 14Japan567 cities10.8
- 15Bosnia and Herzegovina4 cities10.7
- 16Switzerland11 cities10.2
- 17Slovakia42 cities9.9
- 18Greece10 cities9.8
- 19Czechia17 cities9.3
- 20Hungary12 cities, was 49.2
+ 25 more countries, 9.0 µg/m³ and below
- 28United States856 cities8.0
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.