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 20 Jan 2025: Pakistan 166.2 µg/m³, India 96.4 µg/m³ and China 43.3 µg/m³.
- 1Pakistan3 cities166.2
- 2India5 cities96.4
- 3China4 cities43.3
- 4Thailand16 cities40.9
- 5Serbia10 cities34.0
- 6Hong Kong13 cities32.1
- 7Bulgaria5 cities32.0
- 8Slovenia12 cities24.0
- 9Romania10 cities22.8
- 10Hungary9 cities21.4
- 11Poland64 cities21.1
- 12Mexico13 cities20.2
- 13South Korea141 cities19.6
- 14Slovakia42 cities19.6
- 15Chile46 cities17.3
- 16Peru5 cities, was 1515.9
- 17Taiwan43 cities15.5
- 18Austria36 cities14.7
- 19Greece5 cities14.0
- 20Belgium45 cities13.7
+ 22 more countries, the next at 13.3 µg/m³
- 33United States829 cities7.2
Not counted on this day, too few cities measured: Czechia since 18 Jan 2025, Singapore since 16 Jan 2025, Croatia since 15 Jan 2025 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.