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 20 Apr 2023: China 55.9 µg/m³, India 51.4 µg/m³ and Pakistan 36.1 µg/m³.
- 1China3 cities55.9
- 2India3 cities51.4
- 3Pakistan4 cities36.1
- 4Thailand52 cities33.6
- 5South Africa4 cities28.6
- 6Chile45 cities25.6
- 7Mexico43 cities22.2
- 8Peru5 cities16.4
- 9Hong Kong9 cities14.3
- 10Poland60 cities13.5
- 11Romania7 cities12.6
- 12Czechia28 cities12.5
- 13Greece8 cities12.2
- 14Slovakia25 cities11.8
- 15Bulgaria6 cities11.2
- 16Hungary7 cities11.2
- 17Italy15 cities9.8
- 18Belgium37 cities8.9
- 19Spain89 cities8.3
- 20United Kingdom55 cities8.1
+ 15 more countries, 8.0 µg/m³ and below
- 26United States688 cities7.2
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.