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 21 Dec 2024: Pakistan 226.0 µg/m³, India 128.0 µg/m³ and Bosnia and Herzegovina 113.8 µg/m³.
- 1Pakistan3 cities226.0
- 2India4 cities128.0
- 3Bosnia and Herzegovina3 cities113.8
- 4Serbia25 cities56.7
- 5China4 cities32.5
- 6Hong Kong12 cities28.9
- 7Thailand16 cities28.6
- 8Slovenia12 cities25.9
- 9Romania10 cities22.1
- 10Croatia6 cities21.9
- 11Bulgaria8 cities20.3
- 12Greece9 cities18.0
- 13Chile46 cities17.8
- 14Peru18 cities17.2
- 15South Korea141 cities16.7
- 16Taiwan43 cities14.9
- 17Hungary11 cities14.8
- 18Mexico10 cities13.5
- 19Slovakia42 cities11.9
- 20Spain122 cities11.5
+ 25 more countries, the next at 10.6 µg/m³
- 31United States825 cities6.7
Not counted on this day, too few cities measured: France since 18 Dec 2024, Martinique since 18 Dec 2024, Puerto Rico since 7 Dec 2024 and 3 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.