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 7 Feb 2025: Pakistan 95.6 µg/m³, India 92.1 µg/m³ and Thailand 50.2 µg/m³.
- 1Pakistan4 cities95.6
- 2India5 cities92.1
- 3Thailand16 cities50.2
- 4Serbia14 cities39.3
- 5China4 cities39.0
- 6Romania10 cities28.3
- 7Poland75 cities23.2
- 8South Korea141 cities22.2
- 9Slovenia12 cities22.2
- 10Hong Kong13 cities21.0
- 11Hungary9 cities20.7
- 12Slovakia42 cities19.0
- 13Chile45 cities17.7
- 14Mexico14 cities16.9
- 15Belgium45 cities16.8
- 16Peru5 cities, was 1516.6
- 17Taiwan43 cities16.0
- 18Greece5 cities15.2
- 19Austria36 cities15.0
- 20United Kingdom4 cities14.9
+ 19 more countries, 14.9 µg/m³ and below
- 31United States804 cities7.5
Not counted on this day, too few cities measured: Bulgaria since 4 Feb 2025, Luxembourg since 2 Feb 2025, Czechia since 18 Jan 2025 and 5 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.