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 18 Dec 2025: Pakistan 232.7 µg/m³, Bosnia and Herzegovina 83.2 µg/m³ and India 66.0 µg/m³.
- 1Pakistan13 cities232.7
- 2Bosnia and Herzegovina4 cities83.2
- 3India239 cities66.0
- 4North Macedonia13 cities65.2
- 5Ghana3 cities33.3
- 6Peru6 cities31.8
- 7Bulgaria7 cities25.4
- 8Poland63 cities23.8
- 9Romania17 cities23.6
- 10Slovenia12 cities, was 1221.9
- 11Hong Kong13 cities21.5
- 12Mexico52 cities20.2
- 13South Korea140 cities19.4
- 14Thailand73 cities19.0
- 15Hungary13 cities18.9
- 16Laos3 cities16.6
- 17Taiwan45 cities16.4
- 18Chile37 cities16.3
- 19Greece10 cities16.2
- 20Slovakia16 cities, was 3313.9
+ 23 more countries, 12.7 µg/m³ and below
- 32United States862 cities7.7
Not counted on this day, too few cities measured: Czechia since 18 Dec 2025, Martinique since 17 Dec 2025, Malta since 16 Dec 2025 and 7 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.