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 29 Jan 2023: Pakistan 132.5 µg/m³, India 103.2 µg/m³ and Thailand 30.7 µg/m³.
- 1Pakistan3 cities132.5
- 2India3 cities103.2
- 3Thailand44 cities30.7
- 4China3 cities28.7
- 5Bulgaria5 cities26.6
- 6Peru4 cities23.5
- 7Hong Kong9 cities23.3
- 8Greece9 cities23.2
- 9Mexico9 cities22.0
- 10Romania4 cities20.3
- 11Chile39 cities18.6
- 12Poland63 cities17.6
- 13Italy5 cities15.4
- 14Slovakia19 cities15.1
- 15Hungary4 cities15.0
- 16Czechia25 cities13.7
- 17France58 cities10.8
- 18The Netherlands28 cities9.7
- 19Norway20 cities9.0
- 20United Kingdom34 cities8.6
+ 7 more countries, 8.2 µg/m³ and below
- 23United States626 cities7.5
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.