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 30 Jan 2023: Pakistan 129.2 µg/m³, India 101.9 µg/m³ and Thailand 31.8 µg/m³.
- 1Pakistan3 cities129.2
- 2India3 cities101.9
- 3Thailand54 cities31.8
- 4China3 cities28.8
- 5Bulgaria5 cities26.6
- 6Peru4 cities23.4
- 7Hong Kong10 cities23.2
- 8Mexico9 cities21.6
- 9Greece10 cities20.4
- 10Chile41 cities18.2
- 11Poland66 cities18.0
- 12Romania5 cities17.7
- 13South Africa3 cities17.1
- 14Slovakia23 cities15.5
- 15Italy6 cities14.6
- 16Hungary5 cities14.3
- 17Czechia26 cities13.8
- 18France61 cities11.0
- 19The Netherlands29 cities9.7
- 20Norway20 cities8.8
+ 9 more countries, 8.4 µg/m³ and below
- 24United States647 cities7.5
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.