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 20 Aug 2025: Chile 36.8 µg/m³, Pakistan 36.4 µg/m³ and Peru 26.5 µg/m³.
- 1Chile48 cities36.8
- 2Pakistan11 cities36.4
- 3Peru5 cities26.5
- 4Philippines3 cities22.8
- 5Ghana3 cities22.3
- 6India226 cities20.7
- 7New Zealand10 cities15.2
- 8Mexico39 cities12.6
- 9Italy28 cities, was 712.1
- 10Malta4 cities11.9
- 11South Korea140 cities11.7
- 12Brazil3 cities11.6
- 13Spain100 cities11.1
- 14Bosnia and Herzegovina4 cities10.8
- 15Greece9 cities10.4
- 16Slovakia41 cities10.3
- 17Hong Kong13 cities10.1
- 18Martinique3 cities9.8
- 19Canada114 cities9.7
- 20Romania11 cities9.7
+ 26 more countries, 9.5 µg/m³ and below
- 26United States854 cities8.4
Not counted on this day, too few cities measured: 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.