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 31 Jan 2023: Pakistan 128.8 µg/m³, India 102.9 µg/m³ and Thailand 32.5 µg/m³.
- 1Pakistan3 cities128.8
- 2India3 cities102.9
- 3Thailand53 cities32.5
- 4China3 cities29.1
- 5Bulgaria5 cities25.3
- 6Peru4 cities22.9
- 7Hong Kong9 cities22.8
- 8Mexico9 cities21.9
- 9Greece9 cities21.4
- 10Chile42 cities18.2
- 11Poland67 cities17.9
- 12Romania5 cities17.2
- 13South Africa3 cities16.8
- 14Italy6 cities15.2
- 15Slovakia23 cities14.6
- 16Hungary5 cities14.4
- 17Czechia25 cities12.5
- 18France60 cities11.0
- 19The Netherlands29 cities9.5
- 20Norway20 cities8.7
+ 9 more countries, the next at 8.5 µg/m³
- 23United States648 cities7.4
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.