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 8 Jun 2025: Chile 48.3 µg/m³, Peru 35.4 µg/m³ and India 31.0 µg/m³.
- 1Chile47 cities48.3
- 2Peru4 cities35.4
- 3India192 cities31.0
- 4Mexico46 cities19.6
- 5South Korea140 cities17.3
- 6Thailand78 cities13.2
- 7New Zealand6 cities12.6
- 8Hong Kong13 cities12.0
- 9Serbia37 cities11.6
- 10Japan570 cities10.6
- 11Malta4 cities10.1
- 12Taiwan45 cities9.8
- 13Greece5 cities9.3
- 14Latvia4 cities8.8
- 15Poland73 cities8.7
- 16Slovakia41 cities8.4
- 17Italy10 cities8.3
- 18Canada112 cities8.2
- 19Bosnia and Herzegovina5 cities7.6
- 20Romania10 cities7.6
+ 20 more countries, 7.5 µg/m³ and below
- 23United States833 cities7.0
Not counted on this day, too few cities measured: Laos since 8 Jun 2025, Lithuania since 25 May 2025, Martinique since 3 May 2025 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.