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 29 Jan 2025: Pakistan 109.1 µg/m³, India 94.7 µg/m³ and Thailand 48.3 µg/m³.
- 1Pakistan4 cities109.1
- 2India5 cities94.7
- 3Thailand16 cities48.3
- 4China4 cities45.0
- 5Bulgaria5 cities36.9
- 6Serbia10 cities34.5
- 7Romania10 cities29.8
- 8Hong Kong13 cities25.9
- 9South Korea141 cities22.5
- 10Slovenia12 cities21.9
- 11Poland73 cities20.8
- 12Mexico15 cities19.7
- 13Hungary9 cities18.9
- 14Slovakia42 cities18.5
- 15Chile46 cities17.5
- 16Taiwan43 cities16.9
- 17Greece5 cities16.4
- 18Peru5 cities, was 1516.3
- 19Austria36 cities15.1
- 20Belgium45 cities13.4
+ 20 more countries, 13.0 µg/m³ and below
- 32United States814 cities7.1
Not counted on this day, too few cities measured: Luxembourg since 23 Jan 2025, Czechia since 18 Jan 2025, Singapore since 16 Jan 2025 and 4 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.