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 17 May 2024: Laos 43.0 µg/m³, India 36.9 µg/m³ and Pakistan 35.4 µg/m³.
- 1Laos3 cities43.0
- 2India5 cities36.9
- 3Pakistan4 cities35.4
- 4Chile45 cities33.0
- 5Thailand84 cities, was 1528.4
- 6China3 cities27.5
- 7Peru12 cities23.7
- 8Mexico10 cities22.0
- 9Taiwan43 cities16.0
- 10South Korea141 cities15.8
- 11Hong Kong12 cities, was 1312.8
- 12Serbia24 cities12.2
- 13Malta5 cities11.4
- 14Poland75 cities11.2
- 15New Zealand5 cities11.1
- 16Singapore5 cities11.1
- 17Greece7 cities10.4
- 18Japan562 cities10.1
- 19Slovakia38 cities9.4
- 20Belgium44 cities9.2
+ 27 more countries, 9.1 µg/m³ and below
- 37United States807 cities5.9
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 2 May 2024, Montenegro since 26 Mar 2024 and Switzerland since 20 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.