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 13 Jul 2025: Chile 51.0 µg/m³, Pakistan 40.0 µg/m³ and Peru 28.0 µg/m³.
- 1Chile47 cities51.0
- 2Pakistan9 cities40.0
- 3Peru5 cities28.0
- 4India209 cities21.1
- 5New Zealand10 cities14.7
- 6South Korea140 cities13.4
- 7Japan565 cities13.2
- 8Italy15 cities, was 2012.1
- 9Mexico31 cities11.9
- 10Bosnia and Herzegovina5 cities11.3
- 11Slovakia40 cities10.4
- 12Spain102 cities, was 879.9
- 13Hungary4 cities, was 129.7
- 14Greece5 cities8.7
- 15Switzerland9 cities8.5
- 16Slovenia12 cities8.5
- 17United States836 cities8.3
- 18Romania10 cities7.9
- 19Poland59 cities7.8
- 20Hong Kong13 cities7.5
+ 17 more countries, 7.2 µg/m³ and below
Not counted on this day, too few cities measured: Serbia since 10 Jul 2025, Thailand since 10 Jul 2025, Taiwan since 10 Jul 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.