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 30 Mar 2025: Thailand 52.8 µg/m³, India 42.7 µg/m³ and Poland 25.0 µg/m³.
- 1Thailand71 cities52.8
- 2India236 cities42.7
- 3Poland72 cities25.0
- 4Chile42 cities24.4
- 5South Korea141 cities23.7
- 6Serbia36 cities, was 1223.5
- 7Belgium44 cities21.9
- 8Mexico43 cities, was 1421.9
- 9Malta5 cities19.1
- 10Latvia4 cities18.2
- 11Slovakia42 cities18.1
- 12The Netherlands36 cities16.8
- 13Hungary5 cities16.5
- 14Romania9 cities16.1
- 15Peru6 cities15.7
- 16Japan553 cities15.5
- 17Hong Kong12 cities15.4
- 18Taiwan44 cities15.4
- 19Germany234 cities14.7
- 20United Kingdom5 cities14.6
+ 18 more countries, 13.2 µg/m³ and below
- 32United States830 cities6.7
Not counted on this day, too few cities measured: Laos since 28 Mar 2025, Lithuania since 28 Mar 2025, Luxembourg since 28 Mar 2025 and 7 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.