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 23 Feb 2026: Pakistan 107.3 µg/m³, Kazakhstan 51.3 µg/m³ and Ghana 31.2 µg/m³.
- 1Pakistan13 cities107.3
- 2Kazakhstan4 cities51.3
- 3Ghana3 cities31.2
- 4Thailand84 cities29.5
- 5Laos3 cities28.7
- 6Hong Kong13 cities25.9
- 7Poland59 cities25.2
- 8Senegal3 cities22.2
- 9Latvia4 cities22.1
- 10North Macedonia10 cities21.8
- 11Taiwan44 cities20.8
- 12Mexico52 cities20.5
- 13South Korea141 cities19.4
- 14Czechia3 cities18.9
- 15Romania29 cities18.9
- 16Hungary13 cities17.8
- 17Chile46 cities17.2
- 18Slovenia12 cities15.8
- 19Bosnia and Herzegovina6 cities15.6
- 20Peru6 cities15.4
+ 25 more countries, 15.2 µg/m³ and below
- 36United States855 cities6.2
Not counted on this day, too few cities measured: India since 23 Feb 2026, Malta since 22 Feb 2026, Philippines since 22 Feb 2026 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 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.