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 18 Sep 2024: Pakistan 62.7 µg/m³, Chile 27.3 µg/m³ and Peru 26.9 µg/m³.
- 1Pakistan3 cities62.7
- 2Chile45 cities27.3
- 3Peru16 cities26.9
- 4China3 cities22.2
- 5India5 cities22.2
- 6Thailand19 cities16.0
- 7Poland72 cities15.1
- 8Hong Kong13 cities13.6
- 9Singapore5 cities12.4
- 10Hungary4 cities11.7
- 11Taiwan43 cities10.1
- 12Serbia24 cities9.2
- 13Canada120 cities7.9
- 14Mexico3 cities7.7
- 15The Netherlands20 cities7.7
- 16South Korea141 cities7.3
- 17United States804 cities6.7
- 18Japan526 cities6.3
- 19New Zealand5 cities5.9
- 20Australia35 cities5.5
+ 4 more countries, 4.4 µg/m³ and below
Not counted on this day, too few cities measured: Belgium since 17 Aug 2024, Switzerland since 17 Aug 2024, Germany since 17 Aug 2024 and 21 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.