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 19 Oct 2025: Pakistan 71.5 µg/m³, India 32.9 µg/m³ and Peru 27.0 µg/m³.
- 1Pakistan11 cities71.5
- 2India220 cities32.9
- 3Peru5 cities27.0
- 4Chile46 cities20.6
- 5Philippines3 cities17.8
- 6Bosnia and Herzegovina5 cities15.5
- 7North Macedonia11 cities12.3
- 8Taiwan42 cities11.8
- 9Mexico46 cities11.7
- 10Hungary4 cities, was 1210.6
- 11Thailand57 cities10.5
- 12Poland62 cities10.2
- 13Hong Kong13 cities9.2
- 14Brazil3 cities9.0
- 15Latvia4 cities8.8
- 16Switzerland10 cities8.6
- 17Romania10 cities8.4
- 18France37 cities8.0
- 19Belgium48 cities7.8
- 20Montenegro5 cities7.8
+ 20 more countries, 7.8 µg/m³ and below
- 34United States873 cities6.1
Not counted on this day, too few cities measured: Ghana since 19 Oct 2025, Martinique since 19 Oct 2025, Norway since 19 Oct 2025 and 8 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.