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 10 May 2023: India 44.7 µg/m³, China 36.9 µg/m³ and Pakistan 36.1 µg/m³.
- 1India3 cities44.7
- 2China3 cities36.9
- 3Pakistan4 cities36.1
- 4Chile42 cities32.1
- 5Thailand10 cities31.3
- 6Mexico21 cities21.8
- 7Serbia3 cities14.7
- 8Poland50 cities13.0
- 9Czechia30 cities12.4
- 10Greece8 cities12.4
- 11Belgium37 cities11.0
- 12Hungary7 cities10.8
- 13Singapore5 cities10.6
- 14Slovakia24 cities10.5
- 15Romania7 cities10.1
- 16United Kingdom5 cities9.8
- 17Italy22 cities9.4
- 18Bulgaria7 cities8.9
- 19The Netherlands20 cities8.9
- 20Austria23 cities8.7
+ 13 more countries, 8.4 µg/m³ and below
- 25United States688 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.