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 4 May 2024: Laos 60.0 µg/m³, India 48.8 µg/m³ and Pakistan 43.6 µg/m³.
- 1Laos3 cities60.0
- 2India4 cities48.8
- 3Pakistan3 cities43.6
- 4Thailand81 cities, was 1332.2
- 5Chile46 cities29.2
- 6China3 cities26.1
- 7Mexico11 cities22.1
- 8Peru14 cities21.6
- 9South Korea141 cities17.5
- 10Malta5 cities12.2
- 11Taiwan43 cities11.9
- 12Slovakia39 cities10.8
- 13Poland78 cities10.6
- 14Hong Kong12 cities10.5
- 15The Netherlands36 cities10.4
- 16Czechia38 cities9.8
- 17Lithuania4 cities9.8
- 18Singapore5 cities9.7
- 19Latvia4 cities9.5
- 20Japan565 cities9.4
+ 27 more countries, 9.4 µg/m³ and below
- 35United States802 cities6.0
Not counted on this day, too few cities measured: Austria since 26 Apr 2024, Bosnia and Herzegovina since 26 Apr 2024, Montenegro since 22 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.