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 30 days to 22 Sep 2024: Pakistan 55.5 µg/m³, Chile 30.8 µg/m³ and Brazil 27.6 µg/m³.
- 1Pakistan3 cities55.5
- 2Chile45 cities30.8
- 3Brazil33 cities27.6
- 4Peru14 cities24.6
- 5India5 cities21.3
- 6China3 cities21.1
- 7Hungary4 cities16.9
- 8Poland71 cities15.8
- 9Singapore6 cities15.1
- 10Serbia10 cities14.9
- 11Thailand14 cities13.6
- 12Hong Kong13 cities12.0
- 13Taiwan43 cities11.4
- 14South Korea141 cities10.7
- 15The Netherlands20 cities9.3
- 16United Kingdom64 cities8.6
- 17Mexico3 cities7.9
- 18Japan546 cities7.3
- 19Bulgaria5 cities7.2
- 20United States815 cities7.0
+ 5 more countries, the next at 6.8 µg/m³
Not counted on this day, too few cities measured: Belgium since 24 Aug 2024, Switzerland since 24 Aug 2024, Germany since 24 Aug 2024 and 19 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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.