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 28 Jan 2023: Pakistan 103.6 µg/m³, India 99.7 µg/m³ and Thailand 40.4 µg/m³.
- 1Pakistan3 cities103.6
- 2India3 cities99.7
- 3Thailand59 cities40.4
- 4China3 cities30.6
- 5Hong Kong11 cities26.2
- 6Mexico44 cities23.2
- 7Poland69 cities22.5
- 8Kosovo3 cities19.8
- 9Hungary7 cities19.7
- 10Slovakia25 cities18.4
- 11Chile42 cities17.7
- 12France69 cities17.0
- 13Greece10 cities16.5
- 14Peru5 cities16.0
- 15Italy15 cities15.7
- 16Czechia30 cities15.2
- 17South Africa4 cities14.8
- 18Bulgaria7 cities14.3
- 19The Netherlands29 cities14.2
- 20United Kingdom47 cities13.6
+ 13 more countries, 11.8 µg/m³ and below
- 26United States677 cities7.1
Not counted on this day, too few cities measured: Austria since 19 Jan 2023, Belgium since 19 Jan 2023, Germany since 19 Jan 2023 and 7 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.