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 5 Apr 2026: Laos 122.4 µg/m³, Kazakhstan 38.9 µg/m³ and India 30.8 µg/m³.
- 1Laos3 cities122.4
- 2Kazakhstan4 cities38.9
- 3India242 cities30.8
- 4Pakistan13 cities29.1
- 5Thailand85 cities29.0
- 6Ghana3 cities23.3
- 7Peru6 cities23.1
- 8Chile47 cities22.6
- 9Philippines3 cities22.3
- 10South Korea141 cities21.3
- 11Serbia6 cities18.1
- 12Senegal4 cities17.3
- 13Mexico52 cities15.9
- 14Taiwan44 cities15.7
- 15Hong Kong13 cities15.5
- 16Poland60 cities14.1
- 17North Macedonia13 cities13.5
- 18Romania28 cities12.6
- 19Bosnia and Herzegovina5 cities12.2
- 20Latvia3 cities11.1
+ 31 more countries, 10.5 µg/m³ and below
- 38United States879 cities6.2
Not counted on this day, too few cities measured: Kyrgyzstan since 25 Mar 2026, Czechia since 18 Mar 2026 and Spain since 11 Feb 2026.
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.