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 4 May 2024: Laos 59.8 µg/m³, India 47.3 µg/m³ and China 37.8 µg/m³.
- 1Laos3 cities59.8
- 2India5 cities47.3
- 3China4 cities37.8
- 4Thailand82 cities, was 1530.6
- 5Pakistan3 cities29.9
- 6Chile46 cities27.0
- 7Peru6 cities25.8
- 8Mexico11 cities20.1
- 9South Korea141 cities19.9
- 10Taiwan43 cities17.7
- 11Serbia24 cities13.7
- 12Hong Kong12 cities, was 1313.5
- 13Poland74 cities12.2
- 14Japan518 cities11.4
- 15Malta5 cities11.4
- 16Greece7 cities11.3
- 17North Macedonia9 cities11.3
- 18Singapore5 cities10.8
- 19Slovakia35 cities10.4
- 20Czechia38 cities9.1
+ 26 more countries, 9.0 µg/m³ and below
- 38United States798 cities5.7
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 2 May 2024, Montenegro since 26 Mar 2024, Switzerland since 20 Mar 2024 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.