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 17 Dec 2024: Pakistan 115.4 µg/m³, India 76.5 µg/m³ and Bosnia and Herzegovina 69.8 µg/m³.
- 1Pakistan3 cities115.4
- 2India5 cities76.5
- 3Bosnia and Herzegovina4 cities69.8
- 4Serbia25 cities37.8
- 5China3 cities31.1
- 6Thailand16 cities26.4
- 7Slovenia11 cities21.9
- 8Hong Kong13 cities21.2
- 9Peru15 cities19.7
- 10Bulgaria8 cities19.6
- 11Romania9 cities18.9
- 12Croatia5 cities18.5
- 13Hungary11 cities18.2
- 14Chile47 cities17.9
- 15Poland73 cities17.8
- 16Mexico11 cities17.0
- 17Greece9 cities16.2
- 18Slovakia36 cities15.0
- 19South Korea141 cities14.4
- 20Taiwan43 cities12.2
+ 24 more countries, 11.3 µg/m³ and below
- 35United States820 cities6.8
Not counted on this day, too few cities measured: Luxembourg since 7 Dec 2024 and Lithuania since 4 Dec 2024.
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.