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 25 Jan 2023: India 114.9 µg/m³, Pakistan 100.9 µg/m³ and Thailand 32.8 µg/m³.
- 1India3 cities114.9
- 2Pakistan3 cities100.9
- 3Thailand59 cities32.8
- 4China3 cities32.1
- 5Mexico47 cities25.6
- 6Hong Kong11 cities25.2
- 7Poland69 cities21.1
- 8Chile42 cities18.1
- 9Peru5 cities17.3
- 10Hungary6 cities16.5
- 11The Netherlands29 cities16.5
- 12France67 cities16.2
- 13South Africa4 cities16.0
- 14Czechia29 cities15.3
- 15Slovakia25 cities15.3
- 16Greece9 cities15.2
- 17United Kingdom44 cities14.5
- 18Italy15 cities11.6
- 19Bulgaria7 cities10.7
- 20Norway20 cities10.6
+ 12 more countries, 10.4 µg/m³ and below
- 25United States665 cities7.0
Not counted on this day, too few cities measured: Kosovo since 20 Jan 2023, Austria since 19 Jan 2023, Belgium since 19 Jan 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.