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 18 Apr 2024: Laos 54.2 µg/m³, India 42.0 µg/m³ and Thailand 34.2 µg/m³.
- 1Laos3 cities54.2
- 2India5 cities42.0
- 3Thailand81 cities, was 1334.2
- 4China4 cities32.9
- 5Pakistan3 cities27.9
- 6Chile46 cities25.6
- 7South Korea141 cities24.1
- 8Peru6 cities22.8
- 9Taiwan43 cities20.9
- 10Mexico10 cities19.5
- 11Hong Kong11 cities16.5
- 12Malta5 cities15.4
- 13Serbia24 cities15.2
- 14Japan520 cities14.0
- 15North Macedonia9 cities13.3
- 16Greece7 cities12.6
- 17Italy39 cities, was 3911.3
- 18Poland77 cities11.0
- 19Bosnia and Herzegovina5 cities10.5
- 20Slovakia38 cities10.2
+ 26 more countries, 9.6 µg/m³ and below
- 36United States782 cities5.3
Not counted on this day, too few cities measured: Belgium since 13 Apr 2024, Montenegro since 22 Mar 2024, Austria since 13 Mar 2024 and 3 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.