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 17 Feb 2025: India 88.8 µg/m³, Pakistan 78.8 µg/m³ and Bosnia and Herzegovina 72.6 µg/m³.
- 1India5 cities88.8
- 2Pakistan4 cities78.8
- 3Bosnia and Herzegovina3 cities72.6
- 4Thailand71 cities, was 1644.3
- 5Serbia18 cities40.3
- 6China4 cities37.7
- 7Czechia5 cities, was 3631.6
- 8Poland75 cities29.6
- 9Slovenia12 cities28.4
- 10Romania9 cities26.8
- 11Bulgaria5 cities25.8
- 12South Korea141 cities22.3
- 13Hungary10 cities22.0
- 14Slovakia42 cities20.7
- 15Chile45 cities19.6
- 16Croatia3 cities19.6
- 17The Netherlands23 cities19.6
- 18Belgium45 cities19.5
- 19Hong Kong13 cities19.2
- 20Austria36 cities18.0
+ 24 more countries, 17.6 µg/m³ and below
- 36United States821 cities7.2
Not counted on this day, too few cities measured: Luxembourg since 2 Feb 2025, Singapore since 16 Jan 2025 and Lithuania since 1 Jan 2025.
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.