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 Sep 2025: Pakistan 36.0 µg/m³, Peru 34.3 µg/m³ and Chile 27.6 µg/m³.
- 1Pakistan11 cities36.0
- 2Peru5 cities34.3
- 3Chile48 cities27.6
- 4Ghana4 cities24.3
- 5India222 cities20.3
- 6Philippines3 cities18.1
- 7Brazil47 cities12.9
- 8Mexico44 cities11.3
- 9Serbia34 cities11.1
- 10Thailand59 cities10.7
- 11Japan559 cities10.2
- 12Malta5 cities9.8
- 13Taiwan41 cities9.4
- 14Greece8 cities9.2
- 15Romania11 cities9.2
- 16Bosnia and Herzegovina4 cities9.1
- 17Italy24 cities9.0
- 18Hungary10 cities8.9
- 19Poland71 cities8.9
- 20South Korea140 cities8.7
+ 27 more countries, the next at 8.6 µg/m³
- 26United States868 cities6.9
Not counted on this day, too few cities measured: Lithuania since 5 Sep 2025 and Luxembourg since 2 Sep 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.