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 11 Jan 2025: Pakistan 186.4 µg/m³, India 126.1 µg/m³ and Bosnia and Herzegovina 79.7 µg/m³.
- 1Pakistan3 cities186.4
- 2India4 cities126.1
- 3Bosnia and Herzegovina3 cities79.7
- 4Serbia19 cities41.6
- 5China4 cities39.6
- 6Thailand16 cities36.3
- 7Hong Kong13 cities33.2
- 8Bulgaria8 cities25.7
- 9Slovenia12 cities23.9
- 10Croatia5 cities21.0
- 11Romania10 cities21.0
- 12Hungary11 cities20.4
- 13Mexico14 cities19.9
- 14Poland68 cities18.8
- 15Greece9 cities18.3
- 16Czechia36 cities18.0
- 17Chile46 cities17.9
- 18Slovakia42 cities17.9
- 19Peru17 cities17.4
- 20South Korea141 cities16.4
+ 25 more countries, 15.7 µg/m³ and below
- 36United States832 cities7.0
Not counted on this day, too few cities measured: Martinique since 9 Jan 2025 and Lithuania since 1 Jan 2025.
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.