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 18 Jan 2025: Pakistan 173.8 µg/m³, India 95.0 µg/m³ and China 42.4 µg/m³.
- 1Pakistan3 cities173.8
- 2India5 cities95.0
- 3China4 cities42.4
- 4Thailand16 cities39.7
- 5Serbia14 cities34.1
- 6Hong Kong13 cities32.5
- 7Bulgaria5 cities29.8
- 8Romania10 cities22.6
- 9Slovenia12 cities21.8
- 10Hungary11 cities21.2
- 11Mexico15 cities20.7
- 12Poland64 cities19.6
- 13Slovakia42 cities19.1
- 14South Korea141 cities19.0
- 15Greece7 cities18.4
- 16Chile45 cities17.4
- 17Peru5 cities, was 1515.8
- 18Taiwan43 cities15.3
- 19Austria36 cities13.8
- 20Belgium45 cities12.2
+ 21 more countries, 11.4 µg/m³ and below
- 32United States835 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.