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 26 Feb 2025: Bosnia and Herzegovina 61.3 µg/m³, Serbia 54.8 µg/m³ and Romania 54.0 µg/m³.
- 1Bosnia and Herzegovina4 cities61.3
- 2Serbia38 cities54.8
- 3Romania9 cities54.0
- 4Pakistan3 cities52.7
- 5Slovenia12 cities51.1
- 6Croatia5 cities50.7
- 7Bulgaria8 cities43.3
- 8India231 cities, was 543.1
- 9Poland72 cities41.1
- 10Slovakia37 cities33.2
- 11Hungary12 cities32.3
- 12Latvia4 cities29.4
- 13Austria36 cities28.9
- 14Thailand86 cities, was 1626.3
- 15Switzerland3 cities, was 1026.0
- 16China3 cities24.1
- 17Hong Kong13 cities20.7
- 18Laos3 cities17.8
- 19Chile35 cities17.7
- 20Germany223 cities17.0
+ 23 more countries, 16.5 µg/m³ and below
- 35United States822 cities7.3
Not counted on this day, too few cities measured: Luxembourg since 26 Feb 2025, Czechia since 25 Feb 2025, Greece since 23 Feb 2025 and 2 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.