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 5 Dec 2025: Pakistan 198.0 µg/m³, India 62.6 µg/m³ and Bosnia and Herzegovina 43.1 µg/m³.
- 1Pakistan11 cities198.0
- 2India235 cities62.6
- 3Bosnia and Herzegovina5 cities43.1
- 4North Macedonia9 cities26.7
- 5Peru4 cities26.7
- 6Montenegro4 cities25.5
- 7Ghana4 cities24.5
- 8Mexico48 cities21.7
- 9Poland62 cities20.4
- 10Hong Kong13 cities19.7
- 11South Korea139 cities18.6
- 12Philippines3 cities17.9
- 13Chile45 cities17.2
- 14Slovenia12 cities16.6
- 15Hungary12 cities, was 416.5
- 16Bulgaria7 cities13.5
- 17Latvia3 cities13.4
- 18Slovakia5 cities13.1
- 19Austria37 cities12.3
- 20Switzerland10 cities10.8
+ 19 more countries, 10.7 µg/m³ and below
- 28United States797 cities6.9
Not counted on this day, too few cities measured: Martinique since 2 Dec 2025, Kosovo since 30 Nov 2025, Luxembourg since 29 Nov 2025 and 9 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.