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 29 Apr 2025: India 36.4 µg/m³, Chile 27.5 µg/m³ and Mexico 24.1 µg/m³.
- 1India216 cities36.4
- 2Chile44 cities27.5
- 3Mexico50 cities24.1
- 4Belgium27 cities15.8
- 5South Korea138 cities15.3
- 6Hong Kong13 cities14.0
- 7Bosnia and Herzegovina5 cities11.6
- 8Japan558 cities11.3
- 9Hungary4 cities, was 1210.9
- 10The Netherlands36 cities10.5
- 11Greece6 cities, was 910.3
- 12Poland58 cities10.2
- 13New Zealand3 cities9.8
- 14United Kingdom61 cities, was 59.6
- 15France55 cities8.8
- 16Romania8 cities8.8
- 17Malta5 cities8.4
- 18Slovakia42 cities8.2
- 19Latvia4 cities7.7
- 20Germany239 cities7.3
+ 16 more countries, 7.1 µg/m³ and below
- 26United States840 cities6.1
Not counted on this day, too few cities measured: Taiwan since 27 Apr 2025, Czechia since 26 Apr 2025, Laos since 26 Apr 2025 and 10 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.