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 27 Apr 2024: Laos 57.0 µg/m³, India 47.4 µg/m³ and Thailand 29.7 µg/m³.
- 1Laos3 cities57.0
- 2India5 cities47.4
- 3Thailand84 cities, was 1329.7
- 4China4 cities29.6
- 5Pakistan3 cities28.3
- 6Chile46 cities28.2
- 7Peru12 cities24.9
- 8Mexico17 cities18.1
- 9Greece8 cities17.0
- 10Taiwan43 cities17.0
- 11Serbia24 cities16.9
- 12Poland72 cities15.4
- 13South Korea140 cities13.7
- 14Singapore5 cities13.0
- 15Hong Kong12 cities11.7
- 16Croatia4 cities9.2
- 17Czechia38 cities9.0
- 18Hungary11 cities9.0
- 19Japan515 cities9.0
- 20New Zealand5 cities8.7
+ 22 more countries, 8.5 µg/m³ and below
- 35United States794 cities5.7
Not counted on this day, too few cities measured: Austria since 26 Apr 2024, Bosnia and Herzegovina since 26 Apr 2024, North Macedonia since 25 Apr 2024 and 8 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.