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 15 May 2025: Peru 36.6 µg/m³, Chile 35.0 µg/m³ and India 33.5 µg/m³.
- 1Peru5 cities36.6
- 2Chile47 cities35.0
- 3India211 cities33.5
- 4Laos3 cities20.1
- 5Mexico49 cities18.5
- 6South Korea140 cities17.9
- 7Hong Kong13 cities13.9
- 8Serbia35 cities12.9
- 9Thailand80 cities12.9
- 10Taiwan45 cities11.4
- 11Malta5 cities11.1
- 12Japan556 cities10.8
- 13Ireland6 cities10.7
- 14New Zealand6 cities10.3
- 15Czechia44 cities, was 129.1
- 16Poland75 cities8.6
- 17Bosnia and Herzegovina5 cities8.5
- 18Italy19 cities8.5
- 19Hungary12 cities, was 128.4
- 20Slovenia12 cities8.2
+ 25 more countries, 8.1 µg/m³ and below
- 35United States824 cities5.8
Not counted on this day, too few cities measured: Luxembourg since 21 Apr 2025.
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.