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 4 Apr 2026: Laos 107.4 µg/m³, Kazakhstan 42.2 µg/m³ and India 31.2 µg/m³.
- 1Laos3 cities107.4
- 2Kazakhstan4 cities42.2
- 3India241 cities31.2
- 4Pakistan13 cities30.5
- 5Thailand85 cities27.9
- 6Ghana3 cities25.1
- 7Peru6 cities24.3
- 8South Korea141 cities22.9
- 9Chile47 cities22.4
- 10Taiwan44 cities18.2
- 11Serbia4 cities17.4
- 12Senegal4 cities16.6
- 13Mexico53 cities16.1
- 14Hong Kong13 cities15.8
- 15Poland59 cities15.6
- 16North Macedonia13 cities12.1
- 17Romania27 cities11.9
- 18Slovakia42 cities11.5
- 19Japan572 cities11.4
- 20Hungary13 cities11.3
+ 29 more countries, 10.8 µg/m³ and below
- 35United States878 cities6.5
Not counted on this day, too few cities measured: Latvia since 4 Apr 2026, Philippines since 28 Mar 2026, Kyrgyzstan since 25 Mar 2026 and 2 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.