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 16 Mar 2025: India 43.7 µg/m³, Serbia 41.4 µg/m³ and Bosnia and Herzegovina 33.5 µg/m³.
- 1India211 cities, was 543.7
- 2Serbia39 cities41.4
- 3Bosnia and Herzegovina4 cities33.5
- 4Poland73 cities32.5
- 5Romania9 cities31.9
- 6Thailand85 cities, was 1626.4
- 7Bulgaria8 cities24.3
- 8Laos3 cities23.1
- 9Slovenia12 cities22.4
- 10Hungary9 cities21.7
- 11Latvia4 cities21.3
- 12Switzerland3 cities, was 1021.2
- 13Slovakia40 cities21.2
- 14South Korea141 cities18.8
- 15Hong Kong13 cities18.5
- 16Chile44 cities18.3
- 17Austria36 cities17.6
- 18Taiwan43 cities17.5
- 19Belgium42 cities17.2
- 20United Kingdom7 cities17.2
+ 18 more countries, 17.1 µg/m³ and below
- 32United States831 cities6.8
Not counted on this day, too few cities measured: China since 14 Mar 2025, Malta since 13 Mar 2025, Pakistan since 13 Mar 2025 and 7 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.