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 19 Jun 2025: Chile 50.5 µg/m³, Peru 31.0 µg/m³ and India 29.5 µg/m³.
- 1Chile47 cities50.5
- 2Peru4 cities31.0
- 3India197 cities29.5
- 4South Korea139 cities17.3
- 5Mexico45 cities16.3
- 6New Zealand6 cities14.3
- 7Thailand77 cities12.0
- 8Serbia38 cities11.9
- 9Brazil46 cities11.4
- 10Hong Kong13 cities10.7
- 11Italy9 cities10.6
- 12Canada112 cities10.2
- 13Japan565 cities9.8
- 14Bosnia and Herzegovina5 cities9.7
- 15Slovakia34 cities9.4
- 16Poland73 cities8.8
- 17Latvia4 cities8.7
- 18Spain69 cities, was 1148.6
- 19Romania7 cities8.6
- 20Taiwan45 cities8.5
+ 14 more countries, the next at 8.3 µg/m³
- 23United States835 cities7.9
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 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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.