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 1 May 2023: China 49.2 µg/m³, India 49.0 µg/m³ and Pakistan 36.4 µg/m³.
- 1China3 cities49.2
- 2India3 cities49.0
- 3Pakistan4 cities36.4
- 4Thailand10 cities34.9
- 5Chile43 cities26.5
- 6Mexico41 cities22.0
- 7Poland56 cities13.6
- 8Czechia30 cities13.5
- 9Greece8 cities12.3
- 10Belgium37 cities11.9
- 11Hungary8 cities11.7
- 12Romania7 cities11.2
- 13Slovakia24 cities11.2
- 14Bulgaria6 cities10.3
- 15United Kingdom41 cities9.7
- 16Brazil32 cities9.6
- 17Italy18 cities9.6
- 18The Netherlands30 cities9.4
- 19Germany185 cities8.9
- 20Austria22 cities8.8
+ 13 more countries, the next at 8.3 µg/m³
- 25United States683 cities7.0
Not counted on this day, too few cities measured: Hong Kong since 26 Apr 2023, South Africa since 25 Apr 2023, Peru since 24 Apr 2023 and 7 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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.