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 23 Dec 2025: Pakistan 210.6 µg/m³, Bosnia and Herzegovina 87.4 µg/m³ and North Macedonia 79.2 µg/m³.
- 1Pakistan13 cities210.6
- 2Bosnia and Herzegovina5 cities87.4
- 3North Macedonia12 cities79.2
- 4Montenegro5 cities75.9
- 5India238 cities63.1
- 6Ghana3 cities33.3
- 7Romania23 cities29.2
- 8Peru6 cities28.4
- 9Poland65 cities27.4
- 10Bulgaria7 cities26.6
- 11Hungary12 cities25.8
- 12Thailand78 cities24.2
- 13Hong Kong13 cities22.6
- 14Mexico57 cities22.3
- 15South Korea140 cities21.3
- 16Laos3 cities19.2
- 17Greece9 cities17.8
- 18Slovakia17 cities, was 3317.1
- 19Slovenia12 cities, was 1217.0
- 20Chile42 cities16.9
+ 26 more countries, 16.1 µg/m³ and below
- 37United States862 cities6.9
Not counted on this day, too few cities measured: Philippines since 19 Dec 2025, Malta since 16 Dec 2025, Sweden since 14 Dec 2025 and 4 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.