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 7 Jun 2025: Chile 58.6 µg/m³, Peru 58.3 µg/m³ and Pakistan 39.5 µg/m³.
- 1Chile46 cities58.6
- 2Peru4 cities58.3
- 3Pakistan3 cities39.5
- 4India201 cities29.8
- 5South Korea139 cities18.7
- 6Mexico43 cities16.4
- 7Canada112 cities15.3
- 8Thailand77 cities14.9
- 9Serbia38 cities13.4
- 10Italy11 cities, was 2611.7
- 11Hong Kong13 cities11.2
- 12New Zealand7 cities11.2
- 13Slovakia41 cities11.0
- 14Japan567 cities10.7
- 15Greece6 cities10.5
- 16Romania11 cities10.1
- 17Latvia4 cities9.6
- 18Poland73 cities9.5
- 19United States828 cities9.4
- 20Lithuania4 cities8.6
+ 23 more countries, 8.5 µg/m³ and below
Not counted on this day, too few cities measured: Kosovo since 3 Jun 2025, Czechia since 2 Jun 2025, Laos since 1 Jun 2025 and Martinique since 16 May 2025.
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.