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 25 Aug 2025: Pakistan 37.8 µg/m³, Chile 24.9 µg/m³ and Ghana 22.3 µg/m³.
- 1Pakistan11 cities37.8
- 2Chile47 cities24.9
- 3Ghana4 cities22.3
- 4Peru6 cities22.3
- 5Philippines3 cities21.1
- 6India232 cities16.3
- 7Malta5 cities13.4
- 8Brazil3 cities13.1
- 9Mexico42 cities12.2
- 10Japan558 cities12.1
- 11New Zealand10 cities12.1
- 12Spain106 cities11.9
- 13Bosnia and Herzegovina4 cities9.9
- 14Italy28 cities9.8
- 15Greece9 cities9.6
- 16South Korea140 cities9.5
- 17Hungary11 cities8.0
- 18Romania11 cities7.7
- 19Switzerland10 cities7.5
- 20Slovakia42 cities7.4
+ 24 more countries, 7.3 µg/m³ and below
- 29United States856 cities5.9
Not counted on this day, too few cities measured: Luxembourg since 23 Aug 2025, Martinique since 22 Aug 2025, China since 7 Aug 2025 and 3 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.