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 28 Feb 2025: India 69.6 µg/m³, Pakistan 61.9 µg/m³ and Bosnia and Herzegovina 53.6 µg/m³.
- 1India5 cities69.6
- 2Pakistan3 cities61.9
- 3Bosnia and Herzegovina4 cities53.6
- 4Serbia33 cities45.1
- 5Thailand85 cities, was 1635.6
- 6Poland75 cities34.2
- 7Slovenia12 cities33.3
- 8China3 cities30.9
- 9Bulgaria5 cities28.1
- 10Czechia14 cities, was 3627.6
- 11Romania8 cities26.4
- 12Hungary11 cities25.3
- 13Slovakia42 cities24.8
- 14Laos3 cities22.9
- 15Croatia3 cities20.9
- 16Austria36 cities20.8
- 17Switzerland9 cities, was 1020.7
- 18Belgium45 cities20.4
- 19Chile43 cities20.0
- 20Hong Kong13 cities19.9
+ 25 more countries, 19.5 µg/m³ and below
- 39United States828 cities6.9
Not counted on this day, too few cities measured: Lithuania since 23 Feb 2025, Luxembourg since 2 Feb 2025 and Singapore since 16 Jan 2025.
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.