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 17 Jul 2025: Chile 42.6 µg/m³, Pakistan 33.6 µg/m³ and Peru 29.3 µg/m³.
- 1Chile47 cities42.6
- 2Pakistan11 cities33.6
- 3Peru5 cities29.3
- 4India217 cities20.8
- 5Mexico49 cities15.2
- 6New Zealand10 cities13.2
- 7Canada115 cities12.5
- 8Martinique3 cities12.0
- 9Hong Kong13 cities10.5
- 10Italy20 cities, was 910.4
- 11South Korea140 cities10.3
- 12Finland15 cities10.1
- 13Romania11 cities9.3
- 14Spain115 cities9.0
- 15Malta5 cities8.9
- 16Norway20 cities8.6
- 17Greece9 cities8.5
- 18Sweden14 cities8.4
- 19Slovakia41 cities8.4
- 20Lithuania4 cities8.2
+ 20 more countries, 7.7 µg/m³ and below
- 24United States846 cities7.4
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.