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 7 days to 22 Apr 2023: India 62.1 µg/m³, Thailand 48.9 µg/m³ and China 35.3 µg/m³.
- 1India3 cities62.1
- 2Thailand10 cities48.9
- 3China3 cities35.3
- 4Pakistan3 cities26.5
- 5Chile43 cities25.0
- 6Mexico43 cities22.6
- 7Serbia18 cities18.4
- 8Belgium36 cities15.4
- 9Poland65 cities14.8
- 10Czechia29 cities13.8
- 11Singapore5 cities13.6
- 12The Netherlands31 cities12.6
- 13Slovakia25 cities12.4
- 14Ireland4 cities11.8
- 15Germany185 cities11.3
- 16United Kingdom50 cities11.1
- 17Greece7 cities10.9
- 18Romania7 cities9.8
- 19Austria23 cities9.4
- 20Bulgaria7 cities9.4
+ 13 more countries, 9.4 µg/m³ and below
- 28United States668 cities6.6
Not counted on this day, too few cities measured: Peru since 22 Apr 2023, Australia since 15 Apr 2023, Hong Kong since 15 Apr 2023 and 10 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.