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 10 May 2025: India 33.6 µg/m³, Chile 29.6 µg/m³ and Hong Kong 20.3 µg/m³.
- 1India189 cities33.6
- 2Chile47 cities29.6
- 3Hong Kong13 cities20.3
- 4Mexico47 cities20.3
- 5South Korea140 cities14.3
- 6Poland56 cities10.8
- 7Malta5 cities10.5
- 8Japan548 cities10.3
- 9Belgium40 cities10.2
- 10Hungary3 cities, was 1110.1
- 11Bosnia and Herzegovina5 cities9.8
- 12Latvia4 cities9.8
- 13Slovakia35 cities9.5
- 14Lithuania4 cities9.3
- 15Romania7 cities9.3
- 16The Netherlands34 cities9.2
- 17Slovenia12 cities9.1
- 18Italy21 cities9.0
- 19United Kingdom66 cities, was 58.5
- 20New Zealand6 cities8.2
+ 13 more countries, 7.9 µg/m³ and below
- 25United States851 cities6.3
Not counted on this day, too few cities measured: Austria since 5 May 2025, Taiwan since 4 May 2025, Laos since 3 May 2025 and 13 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.