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 8 Apr 2026: Laos 131.7 µg/m³, Thailand 33.9 µg/m³ and Kazakhstan 30.7 µg/m³.
- 1Laos3 cities131.7
- 2Thailand83 cities33.9
- 3Kazakhstan4 cities30.7
- 4Pakistan13 cities30.3
- 5India240 cities28.6
- 6Chile48 cities23.3
- 7Peru6 cities22.2
- 8South Korea141 cities17.7
- 9Serbia7 cities16.7
- 10Mexico52 cities15.0
- 11Hong Kong13 cities14.7
- 12Senegal4 cities13.9
- 13Taiwan44 cities13.3
- 14North Macedonia14 cities12.3
- 15Romania27 cities11.2
- 16Poland61 cities11.0
- 17Italy17 cities9.8
- 18Hungary12 cities9.4
- 19Slovakia41 cities9.3
- 20Japan576 cities9.1
+ 28 more countries, 8.9 µg/m³ and below
- 41United States864 cities5.1
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.