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 28 Feb 2025: Pakistan 51.5 µg/m³, Bulgaria 51.4 µg/m³ and Serbia 48.7 µg/m³.
- 1Pakistan3 cities51.5
- 2Bulgaria5 cities51.4
- 3Serbia38 cities48.7
- 4Hungary5 cities48.3
- 5India234 cities, was 545.0
- 6Poland72 cities41.2
- 7China3 cities37.6
- 8Thailand86 cities, was 1623.8
- 9Hong Kong13 cities20.4
- 10Taiwan43 cities20.3
- 11Chile37 cities18.9
- 12South Korea141 cities18.0
- 13Peru6 cities15.7
- 14Mexico10 cities14.8
- 15Laos3 cities14.4
- 16Japan542 cities9.3
- 17Norway20 cities8.9
- 18United States822 cities7.4
- 19United Kingdom6 cities7.1
- 20The Netherlands22 cities7.0
+ 4 more countries, 5.6 µg/m³ and below
Not counted on this day, too few cities measured: Austria since 27 Feb 2025, Bosnia and Herzegovina since 27 Feb 2025, Belgium since 27 Feb 2025 and 21 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.