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 11 Apr 2026: Laos 128.8 µg/m³, Thailand 35.1 µg/m³ and Pakistan 33.4 µg/m³.
- 1Laos3 cities128.8
- 2Thailand83 cities35.1
- 3Pakistan13 cities33.4
- 4India238 cities30.2
- 5Chile47 cities24.4
- 6Peru6 cities22.5
- 7Kazakhstan4 cities20.2
- 8Serbia8 cities17.4
- 9Mexico56 cities16.2
- 10Taiwan44 cities15.0
- 11South Korea140 cities14.9
- 12Hong Kong13 cities13.3
- 13North Macedonia14 cities12.2
- 14Italy17 cities12.1
- 15Poland59 cities12.1
- 16Senegal4 cities11.2
- 17Greece7 cities9.7
- 18Romania27 cities9.7
- 19Japan575 cities9.1
- 20Slovakia32 cities9.0
+ 28 more countries, 8.8 µg/m³ and below
- 39United States860 cities5.7
Not counted on this day, too few cities measured: Ghana since 8 Apr 2026, Bosnia and Herzegovina since 6 Apr 2026, Philippines since 6 Apr 2026 and 3 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.