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 21 Apr 2024: Laos 52.3 µg/m³, India 47.8 µg/m³ and China 39.6 µg/m³.
- 1Laos3 cities52.3
- 2India5 cities47.8
- 3China4 cities39.6
- 4Thailand81 cities, was 1331.2
- 5Pakistan3 cities27.7
- 6Chile46 cities26.7
- 7South Korea141 cities23.9
- 8Peru12 cities21.4
- 9Mexico10 cities20.3
- 10Taiwan43 cities19.0
- 11Japan526 cities17.4
- 12Serbia24 cities16.0
- 13Hong Kong12 cities13.2
- 14North Macedonia9 cities11.9
- 15Singapore5 cities11.1
- 16Malta5 cities10.9
- 17Poland72 cities9.9
- 18Greece8 cities9.8
- 19Bosnia and Herzegovina5 cities9.5
- 20Romania9 cities8.6
+ 27 more countries, 7.7 µg/m³ and below
- 35United States793 cities5.4
Not counted on this day, too few cities measured: Slovakia since 20 Apr 2024, Montenegro since 22 Mar 2024, Switzerland since 13 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.