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 23 Mar 2025: Laos 42.9 µg/m³, Thailand 39.2 µg/m³ and India 37.7 µg/m³.
- 1Laos3 cities42.9
- 2Thailand75 cities39.2
- 3India235 cities, was 537.7
- 4Serbia38 cities, was 1229.7
- 5South Korea140 cities29.6
- 6Mexico54 cities, was 1425.5
- 7Poland73 cities23.6
- 8Hong Kong13 cities22.1
- 9Chile40 cities20.4
- 10Taiwan44 cities19.6
- 11United Kingdom7 cities18.1
- 12Peru6 cities18.0
- 13Bosnia and Herzegovina4 cities16.0
- 14Slovakia42 cities15.3
- 15Romania10 cities15.1
- 16Ireland4 cities14.3
- 17Greece12 cities12.7
- 18Kosovo8 cities12.5
- 19The Netherlands36 cities12.4
- 20Germany251 cities12.0
+ 22 more countries, 12.0 µg/m³ and below
- 36United States831 cities5.0
Not counted on this day, too few cities measured: Hungary since 23 Mar 2025, Croatia since 14 Mar 2025, Malta since 14 Mar 2025 and 3 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.