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 14 Mar 2025: India 44.1 µg/m³, Serbia 42.4 µg/m³ and Bosnia and Herzegovina 34.7 µg/m³.
- 1India194 cities, was 544.1
- 2Serbia39 cities42.4
- 3Bosnia and Herzegovina4 cities34.7
- 4Poland73 cities34.2
- 5Romania9 cities34.1
- 6Thailand85 cities, was 1628.6
- 7Bulgaria8 cities26.3
- 8Slovenia12 cities24.2
- 9Hungary12 cities24.1
- 10Laos3 cities23.3
- 11Slovakia39 cities22.9
- 12Latvia4 cities21.9
- 13Switzerland3 cities, was 1021.5
- 14Hong Kong13 cities19.5
- 15Belgium42 cities19.4
- 16South Korea141 cities19.0
- 17Germany245 cities18.8
- 18Austria36 cities18.5
- 19Chile44 cities18.4
- 20United Kingdom6 cities18.2
+ 18 more countries, 17.6 µg/m³ and below
- 32United States830 cities6.7
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.