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 30 days to 17 Apr 2026: Laos 106.3 µg/m³, Kazakhstan 35.7 µg/m³ and India 34.9 µg/m³.
- 1Laos3 cities106.3
- 2Kazakhstan4 cities35.7
- 3India239 cities34.9
- 4Pakistan13 cities34.1
- 5Thailand84 cities31.4
- 6Chile47 cities24.2
- 7Peru6 cities24.0
- 8South Korea141 cities23.0
- 9Serbia4 cities18.2
- 10Poland58 cities17.7
- 11Taiwan44 cities17.6
- 12Mexico54 cities16.9
- 13Hong Kong13 cities14.6
- 14Malta5 cities13.8
- 15North Macedonia14 cities13.6
- 16Slovakia42 cities13.4
- 17Romania29 cities13.1
- 18Hungary13 cities12.9
- 19Latvia4 cities12.1
- 20Senegal4 cities12.0
+ 26 more countries, 11.1 µg/m³ and below
- 38United States864 cities6.9
Not counted on this day, too few cities measured: Ghana since 15 Apr 2026, Bosnia and Herzegovina since 13 Apr 2026, Philippines since 8 Apr 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.