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 18 Aug 2025: Chile 39.5 µg/m³, Pakistan 36.8 µg/m³ and Peru 28.3 µg/m³.
- 1Chile47 cities39.5
- 2Pakistan11 cities36.8
- 3Peru5 cities28.3
- 4Philippines3 cities22.8
- 5Ghana3 cities22.6
- 6India223 cities21.0
- 7New Zealand10 cities15.8
- 8Brazil46 cities14.1
- 9Mexico39 cities12.0
- 10Italy28 cities, was 711.8
- 11Malta4 cities11.7
- 12South Korea140 cities11.5
- 13Bosnia and Herzegovina4 cities10.6
- 14Canada114 cities10.4
- 15Slovakia41 cities10.4
- 16Spain100 cities10.2
- 17Hong Kong13 cities10.0
- 18Greece8 cities9.9
- 19Romania11 cities9.7
- 20Czechia16 cities9.6
+ 26 more countries, the next at 9.5 µg/m³
- 26United States853 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, 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.