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 11 Apr 2025: Laos 59.8 µg/m³, Thailand 26.2 µg/m³ and Chile 25.1 µg/m³.
- 1Laos3 cities59.8
- 2Thailand85 cities26.2
- 3Chile47 cities25.1
- 4Taiwan44 cities21.9
- 5South Korea140 cities21.3
- 6Serbia38 cities20.6
- 7Hong Kong13 cities19.7
- 8Peru5 cities16.9
- 9Mexico46 cities, was 1416.0
- 10Italy25 cities14.5
- 11Ireland4 cities13.4
- 12Bosnia and Herzegovina3 cities12.5
- 13Japan548 cities11.0
- 14Belgium44 cities10.7
- 15Slovenia12 cities10.4
- 16United Kingdom68 cities, was 510.2
- 17Hungary11 cities9.9
- 18Slovakia41 cities9.6
- 19France96 cities9.3
- 20Romania11 cities9.3
+ 22 more countries, 8.7 µg/m³ and below
- 33United States843 cities5.7
Not counted on this day, too few cities measured: Czechia since 11 Apr 2025, India since 11 Apr 2025, Estonia since 10 Apr 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.