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 7 days to 11 Jan 2025: Pakistan 109.3 µg/m³, India 92.5 µg/m³ and China 46.9 µg/m³.
- 1Pakistan4 cities109.3
- 2India5 cities92.5
- 3China4 cities46.9
- 4Thailand16 cities45.3
- 5Serbia24 cities32.7
- 6Hong Kong13 cities30.9
- 7Romania10 cities30.3
- 8Bulgaria5 cities29.6
- 9Greece8 cities21.5
- 10Mexico15 cities18.8
- 11Chile44 cities17.3
- 12South Korea141 cities16.5
- 13United Kingdom5 cities15.4
- 14Poland70 cities15.3
- 15Taiwan43 cities15.3
- 16Hungary11 cities13.6
- 17Slovakia42 cities13.5
- 18Peru5 cities, was 1612.9
- 19Ireland7 cities12.6
- 20Latvia4 cities12.0
+ 21 more countries, 11.6 µg/m³ and below
- 29United States821 cities6.6
Not counted on this day, too few cities measured: Czechia since 11 Jan 2025, Croatia since 11 Jan 2025, Bosnia and Herzegovina since 10 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.