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 23 Jan 2023: India 144.6 µg/m³, Pakistan 99.4 µg/m³ and Thailand 30.0 µg/m³.
- 1India3 cities144.6
- 2Pakistan4 cities99.4
- 3Thailand59 cities30.0
- 4Mexico48 cities28.8
- 5China3 cities26.9
- 6Hong Kong10 cities21.9
- 7Poland70 cities20.4
- 8Chile42 cities19.2
- 9Peru5 cities17.3
- 10South Africa10 cities17.3
- 11Czechia28 cities14.4
- 12Greece10 cities14.4
- 13Slovakia25 cities12.6
- 14Hungary6 cities12.5
- 15France69 cities12.1
- 16Romania7 cities11.7
- 17Italy16 cities11.4
- 18Bulgaria7 cities10.8
- 19The Netherlands29 cities10.6
- 20United Kingdom44 cities10.4
+ 10 more countries, 10.1 µg/m³ and below
- 24United States656 cities6.9
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 10 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.