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 Oct 2025: Pakistan 68.6 µg/m³, India 31.0 µg/m³ and Peru 28.3 µg/m³.
- 1Pakistan11 cities68.6
- 2India219 cities31.0
- 3Peru5 cities28.3
- 4Chile46 cities20.6
- 5Philippines3 cities17.7
- 6Ghana4 cities16.8
- 7Bosnia and Herzegovina5 cities14.7
- 8Serbia25 cities13.4
- 9Brazil46 cities11.9
- 10North Macedonia10 cities11.5
- 11Taiwan44 cities11.4
- 12Mexico47 cities11.2
- 13Thailand69 cities10.5
- 14Hungary4 cities, was 1210.2
- 15Poland68 cities10.2
- 16Hong Kong13 cities8.6
- 17Martinique3 cities8.6
- 18Latvia4 cities8.3
- 19Romania11 cities8.2
- 20Switzerland10 cities8.1
+ 24 more countries, the next at 7.8 µg/m³
- 36United States875 cities6.2
Not counted on this day, too few cities measured: Italy since 15 Oct 2025, Ireland since 13 Oct 2025, Estonia since 12 Oct 2025 and 4 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.