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 9 Aug 2025: Chile 41.2 µg/m³, Pakistan 33.2 µg/m³ and Ghana 28.2 µg/m³.
- 1Chile47 cities41.2
- 2Pakistan11 cities33.2
- 3Ghana3 cities28.2
- 4Peru5 cities26.7
- 5India230 cities23.3
- 6Philippines3 cities22.7
- 7Brazil3 cities14.6
- 8New Zealand10 cities12.5
- 9Japan562 cities12.3
- 10South Korea141 cities12.2
- 11Canada114 cities11.6
- 12Hong Kong13 cities11.5
- 13Spain109 cities11.1
- 14Italy28 cities11.1
- 15Mexico40 cities11.1
- 16Greece10 cities9.6
- 17Romania11 cities9.5
- 18Bosnia and Herzegovina5 cities8.8
- 19United States852 cities8.8
- 20Poland62 cities8.4
+ 25 more countries, 8.3 µg/m³ and below
Not counted on this day, too few cities measured: Martinique since 9 Aug 2025, China since 7 Aug 2025, Serbia since 3 Jul 2025 and 2 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.