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 8 Jan 2025: Pakistan 98.5 µg/m³, India 84.9 µg/m³ and Bosnia and Herzegovina 70.0 µg/m³.
- 1Pakistan3 cities98.5
- 2India5 cities84.9
- 3Bosnia and Herzegovina3 cities70.0
- 4Thailand15 cities44.5
- 5China4 cities44.3
- 6Serbia21 cities37.2
- 7Hong Kong13 cities32.2
- 8Bulgaria8 cities29.3
- 9Romania10 cities26.1
- 10Greece9 cities25.6
- 11Mexico22 cities21.7
- 12Croatia6 cities18.2
- 13South Korea141 cities17.7
- 14Chile44 cities17.3
- 15Slovakia41 cities17.1
- 16Poland71 cities15.3
- 17Taiwan43 cities15.2
- 18Hungary12 cities14.9
- 19Peru17 cities13.8
- 20Austria36 cities13.7
+ 26 more countries, 13.2 µg/m³ and below
- 37United States831 cities5.6
Not counted on this day, too few cities measured: 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.