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 31 Aug 2023: Pakistan 39.4 µg/m³, Chile 33.4 µg/m³ and Peru 27.0 µg/m³.
- 1Pakistan4 cities39.4
- 2Chile42 cities33.4
- 3Peru4 cities27.0
- 4India5 cities25.4
- 5China3 cities17.4
- 6Mexico46 cities15.1
- 7Hungary4 cities14.9
- 8Thailand11 cities13.8
- 9Singapore5 cities13.7
- 10Canada113 cities12.0
- 11Bulgaria4 cities9.7
- 12Hong Kong13 cities9.3
- 13United States739 cities8.8
- 14Australia21 cities6.5
- 15Japan515 cities5.8
- 16United Kingdom53 cities3.8
Not counted on this day, too few cities measured: Austria since 27 Aug 2023, Belgium since 27 Aug 2023, Switzerland since 27 Aug 2023 and 20 more countries.
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.