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 24 Jan 2023: India 131.4 µg/m³, Pakistan 95.3 µg/m³ and Thailand 33.0 µg/m³.
- 1India3 cities131.4
- 2Pakistan4 cities95.3
- 3Thailand59 cities33.0
- 4China3 cities28.2
- 5Mexico49 cities26.6
- 6Hong Kong12 cities23.0
- 7Poland70 cities20.6
- 8Chile42 cities18.5
- 9South Africa8 cities17.5
- 10Peru5 cities17.4
- 11Czechia28 cities15.1
- 12Hungary6 cities14.3
- 13Greece10 cities14.1
- 14France68 cities13.8
- 15Slovakia25 cities13.7
- 16United Kingdom45 cities12.9
- 17The Netherlands29 cities12.3
- 18Italy15 cities11.3
- 19Norway20 cities10.5
- 20Romania7 cities10.2
+ 11 more countries, 10.1 µg/m³ and below
- 24United States659 cities7.1
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 9 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.