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 30 days to 12 Jun 2025: Chile 50.0 µg/m³, Peru 34.9 µg/m³ and India 30.2 µg/m³.
- 1Chile47 cities50.0
- 2Peru4 cities34.9
- 3India191 cities30.2
- 4Mexico42 cities19.5
- 5South Korea139 cities16.9
- 6Thailand78 cities12.9
- 7New Zealand6 cities12.5
- 8Serbia38 cities11.7
- 9Hong Kong13 cities10.6
- 10Japan567 cities10.6
- 11Canada112 cities10.0
- 12Malta3 cities9.7
- 13Taiwan45 cities9.5
- 14Italy10 cities9.3
- 15Latvia4 cities8.7
- 16Poland73 cities8.6
- 17Switzerland10 cities8.4
- 18Slovakia41 cities8.4
- 19Spain99 cities, was 1148.2
- 20Romania10 cities8.1
+ 17 more countries, 7.9 µg/m³ and below
- 25United States835 cities7.6
Not counted on this day, too few cities measured: Portugal since 12 Jun 2025, Greece since 11 Jun 2025, Estonia since 10 Jun 2025 and 5 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.