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 27 Jan 2023: Pakistan 132.6 µg/m³, Bulgaria 27.4 µg/m³ and Greece 21.1 µg/m³.
- 1Pakistan3 cities132.6
- 2Bulgaria5 cities27.4
- 3Greece8 cities21.1
- 4Romania4 cities20.7
- 5Chile31 cities18.8
- 6Mexico6 cities18.8
- 7Poland60 cities17.8
- 8Slovakia19 cities14.9
- 9Czechia24 cities13.8
- 10Italy3 cities11.8
- 11France57 cities10.2
- 12The Netherlands27 cities9.4
- 13United Kingdom21 cities9.0
- 14Brazil7 cities8.5
- 15Spain31 cities8.4
- 16Norway17 cities8.4
- 17United States474 cities7.8
- 18Canada45 cities6.6
- 19Sweden6 cities4.5
- 20Finland8 cities3.9
Days missing from the source archive fall in this window, so fewer countries are counted.
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.