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 9 Jan 2025: Pakistan 97.1 µg/m³, India 88.7 µg/m³ and Thailand 47.2 µg/m³.
- 1Pakistan3 cities97.1
- 2India5 cities88.7
- 3Thailand15 cities47.2
- 4Bosnia and Herzegovina3 cities45.3
- 5China4 cities43.8
- 6Serbia22 cities35.0
- 7Hong Kong13 cities31.9
- 8Bulgaria8 cities29.3
- 9Romania10 cities27.6
- 10Greece9 cities25.0
- 11Mexico17 cities21.2
- 12Croatia5 cities17.8
- 13Chile45 cities17.4
- 14Poland72 cities17.0
- 15Taiwan43 cities16.1
- 16South Korea141 cities15.7
- 17Slovakia41 cities15.3
- 18Ireland7 cities14.2
- 19Hungary12 cities13.9
- 20Peru16 cities13.5
+ 25 more countries, 12.2 µg/m³ and below
- 36United States824 cities6.0
Not counted on this day, too few cities measured: Singapore since 9 Jan 2025, Lithuania since 28 Dec 2024, Puerto Rico since 7 Dec 2024 and Kosovo since 24 Nov 2024.
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.