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 18 Mar 2025: India 37.5 µg/m³, Laos 28.2 µg/m³ and Lithuania 26.4 µg/m³.
- 1India223 cities, was 537.5
- 2Laos3 cities28.2
- 3Lithuania4 cities26.4
- 4Thailand85 cities23.0
- 5Mexico53 cities, was 1420.8
- 6Chile46 cities20.6
- 7Poland71 cities18.6
- 8Peru6 cities18.3
- 9South Korea141 cities17.8
- 10Greece9 cities17.7
- 11Serbia39 cities, was 1217.7
- 12Taiwan43 cities17.6
- 13Hong Kong13 cities15.6
- 14Romania10 cities12.5
- 15Latvia4 cities11.6
- 16France106 cities, was 2311.4
- 17Germany236 cities10.6
- 18Ireland6 cities9.6
- 19Bulgaria8 cities9.0
- 20Belgium43 cities8.9
+ 21 more countries, 8.8 µg/m³ and below
- 28United States838 cities6.8
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 18 Mar 2025, Luxembourg since 15 Mar 2025, Croatia since 14 Mar 2025 and 4 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.