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 9 Apr 2026: Laos 128.9 µg/m³, Thailand 34.6 µg/m³ and Pakistan 31.3 µg/m³.
- 1Laos3 cities128.9
- 2Thailand83 cities34.6
- 3Pakistan13 cities31.3
- 4India235 cities28.7
- 5Kazakhstan4 cities25.0
- 6Chile48 cities24.1
- 7Peru6 cities22.6
- 8Serbia7 cities16.6
- 9South Korea140 cities15.8
- 10Mexico54 cities15.7
- 11Hong Kong13 cities15.1
- 12Taiwan44 cities13.8
- 13Senegal4 cities12.3
- 14North Macedonia14 cities11.9
- 15Italy16 cities11.0
- 16Romania27 cities10.6
- 17Poland59 cities10.3
- 18Japan576 cities9.6
- 19Hungary12 cities9.2
- 20Malta5 cities8.7
+ 27 more countries, 8.6 µg/m³ and below
- 38United States863 cities5.4
Not counted on this day, too few cities measured: Slovenia since 9 Apr 2026, Ghana since 8 Apr 2026, Bosnia and Herzegovina since 6 Apr 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.