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 15 Jul 2025: Chile 43.3 µg/m³, Pakistan 34.1 µg/m³ and Peru 30.3 µg/m³.
- 1Chile48 cities43.3
- 2Pakistan11 cities34.1
- 3Peru5 cities30.3
- 4India215 cities20.7
- 5Mexico47 cities15.3
- 6New Zealand10 cities13.5
- 7Martinique3 cities12.7
- 8South Korea140 cities11.0
- 9Japan559 cities10.8
- 10Hong Kong13 cities9.9
- 11Canada116 cities9.0
- 12Italy21 cities, was 99.0
- 13Finland15 cities8.9
- 14Spain120 cities8.8
- 15Romania11 cities8.3
- 16Norway20 cities7.8
- 17Slovakia40 cities7.6
- 18Greece7 cities7.5
- 19United States850 cities7.5
- 20Lithuania4 cities7.4
+ 20 more countries, 7.3 µg/m³ and below
Not counted on this day, too few cities measured: Ireland since 14 Jul 2025, Luxembourg since 10 Jul 2025, Czechia since 3 Jul 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.