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 17 Aug 2025: Chile 40.0 µg/m³, Pakistan 37.1 µg/m³ and Peru 29.0 µg/m³.
- 1Chile47 cities40.0
- 2Pakistan11 cities37.1
- 3Peru5 cities29.0
- 4Ghana3 cities22.9
- 5Philippines3 cities22.7
- 6India222 cities21.1
- 7New Zealand10 cities16.2
- 8Brazil3 cities12.1
- 9Mexico40 cities12.1
- 10Italy28 cities, was 711.8
- 11Malta4 cities11.6
- 12South Korea140 cities11.1
- 13Canada115 cities10.9
- 14Bosnia and Herzegovina5 cities10.5
- 15Hong Kong13 cities10.5
- 16Slovakia41 cities10.4
- 17Spain101 cities9.9
- 18Greece8 cities9.9
- 19Czechia17 cities9.6
- 20Martinique3 cities9.6
+ 26 more countries, 9.6 µg/m³ and below
- 26United States852 cities8.4
Not counted on this day, too few cities measured: 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.