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 4 Feb 2024: China 74.0 µg/m³, India 69.2 µg/m³ and Pakistan 65.3 µg/m³.
- 1China3 cities74.0
- 2India5 cities69.2
- 3Pakistan3 cities65.3
- 4North Macedonia9 cities61.4
- 5Montenegro3 cities50.9
- 6Serbia18 cities, was 349.4
- 7Thailand75 cities, was 1037.1
- 8Italy38 cities32.9
- 9Romania9 cities23.6
- 10Slovakia42 cities23.3
- 11Bulgaria6 cities21.0
- 12Hong Kong11 cities21.0
- 13Peru6 cities19.9
- 14Chile36 cities19.6
- 15Poland75 cities18.1
- 16Czechia38 cities17.9
- 17Croatia4 cities15.8
- 18Hungary10 cities15.6
- 19South Africa14 cities15.4
- 20Spain129 cities15.1
+ 22 more countries, 14.5 µg/m³ and below
- 38United States752 cities6.4
Not counted on this day, too few cities measured: Iceland since 26 Jan 2024, Reunion since 15 Jan 2024 and Malta since 2 Jan 2024. 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.