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 21 Jun 2025: Chile 50.9 µg/m³, Pakistan 46.6 µg/m³ and Peru 29.8 µg/m³.
- 1Chile47 cities50.9
- 2Pakistan3 cities46.6
- 3Peru4 cities29.8
- 4India201 cities29.2
- 5South Korea139 cities16.8
- 6Mexico43 cities15.1
- 7New Zealand6 cities13.7
- 8Serbia38 cities11.8
- 9Thailand76 cities11.7
- 10Italy7 cities, was 2010.8
- 11Canada112 cities10.6
- 12Hong Kong13 cities10.5
- 13Bosnia and Herzegovina4 cities10.0
- 14Japan565 cities9.8
- 15Slovakia28 cities9.5
- 16Spain61 cities9.3
- 17Poland73 cities8.6
- 18Latvia4 cities8.5
- 19Romania6 cities8.5
- 20Taiwan45 cities8.4
+ 14 more countries, 8.3 µg/m³ and below
- 23United States836 cities8.1
Not counted on this day, too few cities measured: Sweden since 21 Jun 2025, Switzerland since 17 Jun 2025, France since 15 Jun 2025 and 9 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.