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 May 2024: Laos 44.7 µg/m³, India 41.2 µg/m³ and Pakistan 34.1 µg/m³.
- 1Laos3 cities44.7
- 2India5 cities41.2
- 3Pakistan4 cities34.1
- 4China4 cities32.1
- 5Chile45 cities31.1
- 6Thailand84 cities, was 1528.3
- 7Peru12 cities23.6
- 8Mexico10 cities22.4
- 9South Korea141 cities17.0
- 10Taiwan43 cities16.1
- 11Hong Kong12 cities, was 1312.8
- 12Serbia24 cities12.6
- 13Poland75 cities11.3
- 14Singapore5 cities10.8
- 15Greece7 cities10.6
- 16Japan524 cities10.5
- 17Malta5 cities10.3
- 18North Macedonia9 cities10.0
- 19New Zealand5 cities9.8
- 20Slovakia38 cities9.3
+ 27 more countries, 9.1 µg/m³ and below
- 37United States804 cities5.9
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 Austria since 18 Mar 2024.
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.