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 19 May 2025: Chile 38.5 µg/m³, Peru 35.5 µg/m³ and India 31.0 µg/m³.
- 1Chile46 cities38.5
- 2Peru6 cities35.5
- 3India217 cities31.0
- 4Mexico42 cities25.2
- 5South Korea139 cities16.4
- 6Thailand79 cities13.4
- 7Japan567 cities12.7
- 8New Zealand6 cities12.0
- 9Taiwan45 cities11.0
- 10Serbia37 cities10.8
- 11Malta5 cities10.6
- 12Laos3 cities9.9
- 13Hong Kong13 cities9.6
- 14United Kingdom68 cities9.3
- 15Belgium45 cities9.1
- 16Latvia4 cities8.4
- 17Italy8 cities, was 268.1
- 18France20 cities, was 1037.6
- 19Poland73 cities7.5
- 20The Netherlands34 cities7.3
+ 19 more countries, 7.2 µg/m³ and below
- 29United States825 cities5.8
Not counted on this day, too few cities measured: Estonia since 19 May 2025, Portugal since 19 May 2025, Greece since 18 May 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.