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 27 Jan 2023: India 96.1 µg/m³, Pakistan 91.2 µg/m³ and Thailand 39.6 µg/m³.
- 1India3 cities96.1
- 2Pakistan3 cities91.2
- 3Thailand61 cities39.6
- 4China3 cities27.8
- 5Hong Kong11 cities25.5
- 6Mexico46 cities22.4
- 7Poland69 cities21.6
- 8Hungary6 cities20.0
- 9Chile42 cities17.6
- 10France67 cities17.3
- 11Greece10 cities17.1
- 12Slovakia25 cities16.9
- 13Peru5 cities16.4
- 14The Netherlands29 cities16.3
- 15South Africa4 cities15.5
- 16Czechia30 cities14.8
- 17Bulgaria7 cities14.3
- 18United Kingdom45 cities14.1
- 19Italy15 cities13.8
- 20Romania7 cities11.8
+ 12 more countries, 10.9 µg/m³ and below
- 25United States670 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 8 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.