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 20 May 2024: Laos 40.7 µg/m³, Chile 37.6 µg/m³ and India 35.8 µg/m³.
- 1Laos3 cities40.7
- 2Chile45 cities37.6
- 3India5 cities35.8
- 4Pakistan4 cities35.7
- 5Thailand84 cities, was 1527.2
- 6China3 cities26.1
- 7Peru12 cities23.2
- 8Mexico9 cities22.5
- 9Taiwan43 cities15.3
- 10Malta5 cities15.0
- 11South Korea141 cities14.0
- 12Hong Kong12 cities12.9
- 13Greece7 cities12.1
- 14Serbia24 cities11.9
- 15New Zealand5 cities11.4
- 16Poland77 cities11.1
- 17Singapore5 cities10.8
- 18Belgium44 cities10.7
- 19The Netherlands36 cities10.3
- 20Latvia4 cities9.6
+ 27 more countries, 9.5 µg/m³ and below
- 37United States809 cities6.0
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 2 May 2024 and Montenegro since 26 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.