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 Apr 2023: China 52.0 µg/m³, India 50.2 µg/m³ and Pakistan 35.4 µg/m³.
- 1China3 cities52.0
- 2India3 cities50.2
- 3Pakistan4 cities35.4
- 4Thailand11 cities34.6
- 5Chile45 cities26.6
- 6Mexico40 cities22.1
- 7Poland57 cities13.5
- 8Czechia29 cities13.0
- 9Greece8 cities11.9
- 10Romania7 cities11.7
- 11Slovakia25 cities11.6
- 12Hungary8 cities11.5
- 13Belgium37 cities11.2
- 14Bulgaria6 cities10.5
- 15Italy16 cities9.7
- 16United Kingdom40 cities9.0
- 17The Netherlands30 cities8.9
- 18Austria22 cities8.5
- 19Germany185 cities8.5
- 20Spain88 cities8.3
+ 11 more countries, 7.9 µg/m³ and below
- 25United States685 cities7.2
Not counted on this day, too few cities measured: Australia since 26 Apr 2023, Hong Kong since 26 Apr 2023, South Africa since 25 Apr 2023 and 8 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.