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 19 Jan 2025: Pakistan 171.2 µg/m³, India 95.6 µg/m³ and China 42.7 µg/m³.
- 1Pakistan3 cities171.2
- 2India5 cities95.6
- 3China4 cities42.7
- 4Thailand16 cities40.4
- 5Serbia10 cities33.2
- 6Hong Kong13 cities32.3
- 7Bulgaria5 cities30.4
- 8Slovenia12 cities23.0
- 9Romania10 cities21.6
- 10Hungary9 cities21.1
- 11Mexico14 cities20.3
- 12Poland64 cities20.2
- 13Slovakia42 cities19.3
- 14South Korea141 cities18.9
- 15Chile46 cities17.3
- 16Greece6 cities16.0
- 17Peru5 cities, was 1515.8
- 18Taiwan43 cities15.3
- 19Austria36 cities14.3
- 20Belgium45 cities13.0
+ 21 more countries, 12.3 µg/m³ and below
- 32United States831 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 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.