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 23 Apr 2023: China 54.7 µg/m³, India 51.4 µg/m³ and Pakistan 35.2 µg/m³.
- 1China3 cities54.7
- 2India3 cities51.4
- 3Pakistan4 cities35.2
- 4Thailand53 cities34.6
- 5Chile45 cities25.8
- 6South Africa5 cities24.8
- 7Mexico41 cities21.8
- 8Peru4 cities16.8
- 9Hong Kong9 cities14.2
- 10Poland62 cities13.0
- 11Czechia29 cities12.6
- 12Greece8 cities11.9
- 13Romania7 cities11.7
- 14Hungary7 cities11.2
- 15Slovakia25 cities11.0
- 16Bulgaria6 cities10.5
- 17Belgium37 cities9.9
- 18Italy15 cities9.2
- 19The Netherlands31 cities8.8
- 20United Kingdom54 cities8.5
+ 15 more countries, 8.2 µg/m³ and below
- 27United States684 cities7.1
Not counted on this day, too few cities measured: Kosovo since 2 Apr 2023, Bosnia and Herzegovina since 30 Mar 2023, Latvia since 30 Mar 2023 and 4 more countries. 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.