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 8 May 2023: India 44.5 µg/m³, China 37.4 µg/m³ and Pakistan 36.2 µg/m³.
- 1India3 cities44.5
- 2China3 cities37.4
- 3Pakistan4 cities36.2
- 4Thailand10 cities31.6
- 5Chile43 cities30.0
- 6Mexico34 cities22.8
- 7Serbia3 cities16.6
- 8Czechia30 cities13.2
- 9Poland56 cities12.9
- 10Greece8 cities12.5
- 11Belgium37 cities11.6
- 12Romania7 cities11.2
- 13Singapore5 cities11.1
- 14Hungary7 cities11.0
- 15Slovakia24 cities11.0
- 16United Kingdom24 cities10.4
- 17Bulgaria7 cities9.4
- 18Italy19 cities9.3
- 19The Netherlands28 cities9.2
- 20Austria23 cities8.9
+ 13 more countries, 8.9 µg/m³ and below
- 25United States687 cities6.9
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.