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 2 Feb 2023: India 90.9 µg/m³, Pakistan 85.8 µg/m³ and Thailand 44.4 µg/m³.
- 1India3 cities90.9
- 2Pakistan4 cities85.8
- 3Thailand66 cities44.4
- 4Laos3 cities43.3
- 5China3 cities29.2
- 6Mexico11 cities21.6
- 7Kosovo6 cities18.8
- 8Bulgaria5 cities18.5
- 9Chile42 cities18.1
- 10Italy13 cities17.2
- 11Romania7 cities16.9
- 12Hungary7 cities16.7
- 13Peru5 cities16.7
- 14Greece9 cities15.4
- 15Poland70 cities14.5
- 16Slovakia25 cities14.3
- 17South Africa9 cities13.8
- 18France69 cities12.9
- 19Norway19 cities10.3
- 20Czechia28 cities10.2
+ 12 more countries, 9.3 µg/m³ and below
- 26United States665 cities7.3
Not counted on this day, too few cities measured: Hong Kong since 2 Feb 2023, Ireland since 1 Feb 2023, Austria 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.