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 7 Aug 2025: Chile 40.1 µg/m³, Pakistan 34.7 µg/m³ and Peru 29.7 µg/m³.
- 1Chile47 cities40.1
- 2Pakistan11 cities34.7
- 3Peru5 cities29.7
- 4India215 cities21.3
- 5Philippines3 cities20.1
- 6New Zealand10 cities16.6
- 7Mexico44 cities13.1
- 8Canada115 cities11.9
- 9South Korea140 cities11.4
- 10Hong Kong13 cities11.2
- 11Martinique3 cities10.6
- 12Greece8 cities10.0
- 13Malta4 cities9.8
- 14Japan564 cities9.5
- 15Romania11 cities9.3
- 16Finland15 cities, was 39.2
- 17Italy26 cities, was 79.1
- 18Spain100 cities8.5
- 19United States851 cities8.4
- 20Poland60 cities8.1
+ 21 more countries, 7.9 µg/m³ and below
Not counted on this day, too few cities measured: Ireland since 31 Jul 2025, Serbia since 10 Jul 2025, Thailand since 10 Jul 2025 and Taiwan since 10 Jul 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.