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 2 Feb 2023: Pakistan 129.3 µg/m³, India 102.8 µg/m³ and Thailand 34.3 µg/m³.
- 1Pakistan3 cities129.3
- 2India3 cities102.8
- 3Thailand51 cities34.3
- 4China3 cities28.8
- 5Bulgaria5 cities23.0
- 6Peru4 cities22.8
- 7Mexico7 cities19.8
- 8Greece9 cities18.9
- 9Chile40 cities18.4
- 10Poland68 cities17.1
- 11Romania5 cities15.1
- 12Italy7 cities14.8
- 13Slovakia23 cities13.9
- 14Czechia24 cities11.7
- 15France59 cities11.1
- 16The Netherlands28 cities9.3
- 17Norway20 cities9.1
- 18Spain34 cities8.6
- 19United Kingdom34 cities8.6
- 20Brazil11 cities7.7
+ 5 more countries, 7.4 µg/m³ and below
- 21United States627 cities7.4
Not counted on this day, too few cities measured: Hong Kong since 2 Feb 2023, Hungary since 2 Feb 2023, Portugal since 2 Feb 2023 and South Africa since 1 Feb 2023. 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.