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 14 Jan 2025: Pakistan 189.5 µg/m³, India 95.1 µg/m³ and China 42.3 µg/m³.
- 1Pakistan3 cities189.5
- 2India5 cities95.1
- 3China4 cities42.3
- 4Serbia19 cities40.1
- 5Thailand16 cities38.4
- 6Hong Kong13 cities32.2
- 7Croatia4 cities25.9
- 8Bulgaria8 cities25.8
- 9Slovenia12 cities23.1
- 10Romania10 cities21.7
- 11Hungary11 cities19.4
- 12Mexico14 cities19.3
- 13Czechia35 cities18.8
- 14Greece9 cities18.6
- 15Poland67 cities18.1
- 16South Korea141 cities18.0
- 17Slovakia42 cities17.8
- 18Chile46 cities17.6
- 19Peru17 cities16.6
- 20Taiwan43 cities15.2
+ 24 more countries, 13.4 µg/m³ and below
- 35United States833 cities7.1
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 12 Jan 2025, 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.