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 27 Jan 2025: Pakistan 112.7 µg/m³, India 95.1 µg/m³ and Thailand 47.9 µg/m³.
- 1Pakistan4 cities112.7
- 2India5 cities95.1
- 3Thailand16 cities47.9
- 4China4 cities46.7
- 5Bulgaria5 cities36.4
- 6Serbia10 cities36.2
- 7Romania10 cities27.9
- 8Hong Kong13 cities27.7
- 9Slovenia12 cities24.6
- 10South Korea141 cities23.3
- 11Hungary9 cities22.7
- 12Poland69 cities21.8
- 13Slovakia42 cities20.3
- 14Mexico13 cities18.0
- 15Chile46 cities17.3
- 16Taiwan43 cities17.0
- 17Austria36 cities16.2
- 18Peru5 cities, was 1515.9
- 19Greece5 cities15.6
- 20Belgium45 cities13.9
+ 20 more countries, 13.3 µg/m³ and below
- 32United States811 cities7.0
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.