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 28 Jun 2025: Chile 50.8 µg/m³, Pakistan 49.0 µg/m³ and India 27.8 µg/m³.
- 1Chile47 cities50.8
- 2Pakistan5 cities49.0
- 3India200 cities27.8
- 4Peru6 cities27.2
- 5South Korea139 cities16.2
- 6New Zealand10 cities14.2
- 7Italy7 cities, was 2014.0
- 8Mexico38 cities13.0
- 9Serbia38 cities12.7
- 10Spain33 cities12.5
- 11Bosnia and Herzegovina4 cities12.1
- 12Thailand76 cities11.9
- 13Canada111 cities11.5
- 14Slovakia25 cities11.0
- 15Slovenia11 cities10.6
- 16Hungary4 cities10.4
- 17Romania7 cities10.0
- 18Japan565 cities9.8
- 19United States838 cities9.0
- 20Poland73 cities8.2
+ 15 more countries, 8.1 µg/m³ and below
Not counted on this day, too few cities measured: Switzerland since 17 Jun 2025, France since 15 Jun 2025, Malta since 14 Jun 2025 and 7 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.