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 16 Jun 2025: Chile 49.5 µg/m³, Peru 32.6 µg/m³ and India 29.6 µg/m³.
- 1Chile47 cities49.5
- 2Peru4 cities32.6
- 3India194 cities29.6
- 4Mexico45 cities18.2
- 5South Korea139 cities16.9
- 6New Zealand6 cities13.1
- 7Thailand77 cities12.5
- 8Serbia38 cities11.6
- 9Hong Kong13 cities10.7
- 10Canada112 cities10.0
- 11Italy8 cities10.0
- 12Japan564 cities10.0
- 13Switzerland10 cities9.6
- 14Spain86 cities, was 1148.8
- 15Poland73 cities8.8
- 16Slovakia39 cities8.7
- 17Taiwan45 cities8.7
- 18Latvia4 cities8.6
- 19Bosnia and Herzegovina5 cities8.4
- 20Romania9 cities8.3
+ 14 more countries, 8.0 µg/m³ and below
- 23United States834 cities7.9
Not counted on this day, too few cities measured: France since 15 Jun 2025, Malta since 14 Jun 2025, Kosovo since 13 Jun 2025 and 8 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.