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 19 Jul 2025: Chile 42.7 µg/m³, Pakistan 34.5 µg/m³ and Peru 27.7 µg/m³.
- 1Chile47 cities42.7
- 2Pakistan11 cities34.5
- 3Peru6 cities27.7
- 4India220 cities20.7
- 5Brazil46 cities16.2
- 6Mexico52 cities15.2
- 7Philippines3 cities15.1
- 8New Zealand10 cities14.7
- 9Canada115 cities13.2
- 10Hong Kong13 cities12.3
- 11Malta5 cities11.0
- 12Italy22 cities, was 910.8
- 13Greece8 cities10.5
- 14Norway20 cities10.1
- 15Martinique3 cities9.6
- 16Finland15 cities9.2
- 17Romania11 cities9.1
- 18Poland59 cities9.0
- 19South Korea140 cities8.9
- 20Lithuania4 cities8.9
+ 23 more countries, the next at 8.9 µg/m³
- 31United States846 cities7.0
Not counted on this day, too few cities measured: Luxembourg since 10 Jul 2025, Czechia since 3 Jul 2025, Serbia since 3 Jul 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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.