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 28 Jan 2023: Pakistan 131.9 µg/m³, India 104.7 µg/m³ and Thailand 32.8 µg/m³.
- 1Pakistan3 cities131.9
- 2India3 cities104.7
- 3Thailand8 cities32.8
- 4Bulgaria5 cities26.8
- 5Hong Kong8 cities23.2
- 6Mexico9 cities22.2
- 7Greece8 cities20.9
- 8Romania4 cities20.4
- 9Chile39 cities18.7
- 10Poland62 cities17.7
- 11Italy5 cities15.4
- 12Slovakia19 cities15.1
- 13Czechia24 cities13.8
- 14France58 cities10.5
- 15The Netherlands28 cities9.2
- 16Norway20 cities9.0
- 17United Kingdom28 cities8.9
- 18Spain35 cities8.1
- 19Brazil8 cities8.0
- 20United States598 cities7.5
+ 3 more countries, 6.1 µg/m³ and below
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.