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 30 days to 18 Dec 2025: Pakistan 226.0 µg/m³, India 64.1 µg/m³ and Bosnia and Herzegovina 59.5 µg/m³.
- 1Pakistan13 cities226.0
- 2India245 cities64.1
- 3Bosnia and Herzegovina5 cities59.5
- 4Montenegro4 cities42.3
- 5North Macedonia12 cities39.1
- 6Ghana3 cities30.0
- 7Peru5 cities27.1
- 8Hong Kong13 cities24.1
- 9Thailand72 cities23.7
- 10Poland63 cities22.3
- 11Mexico45 cities21.2
- 12Romania13 cities, was 1120.0
- 13South Korea139 cities19.9
- 14Slovenia12 cities18.8
- 15Laos3 cities18.5
- 16Hungary12 cities, was 417.4
- 17Bulgaria7 cities16.7
- 18Chile43 cities16.7
- 19Philippines3 cities15.7
- 20Taiwan45 cities15.7
+ 21 more countries, 13.5 µg/m³ and below
- 33United States849 cities7.5
Not counted on this day, too few cities measured: Sweden since 17 Dec 2025, Malta since 16 Dec 2025, Ireland since 15 Dec 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.