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 8 Apr 2025: Laos 59.9 µg/m³, India 42.1 µg/m³ and Thailand 36.5 µg/m³.
- 1Laos3 cities59.9
- 2India228 cities, was 542.1
- 3Thailand86 cities36.5
- 4Serbia39 cities25.4
- 5South Korea140 cities23.5
- 6Chile45 cities22.2
- 7Mexico49 cities, was 1221.2
- 8Poland72 cities20.6
- 9Peru6 cities17.9
- 10Taiwan44 cities17.9
- 11Hong Kong13 cities17.3
- 12Romania10 cities15.7
- 13United Kingdom6 cities15.1
- 14Hungary7 cities14.3
- 15Latvia4 cities14.1
- 16Bosnia and Herzegovina3 cities13.9
- 17Belgium44 cities13.7
- 18Slovakia42 cities13.4
- 19Greece9 cities12.7
- 20Ireland4 cities12.5
+ 22 more countries, 12.3 µg/m³ and below
- 36United States848 cities6.0
Not counted on this day, too few cities measured: Lithuania since 8 Apr 2025, China since 14 Mar 2025, Malta since 13 Mar 2025 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.