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 26 Mar 2024: Pakistan 56.8 µg/m³, China 47.0 µg/m³ and India 46.7 µg/m³.
- 1Pakistan4 cities56.8
- 2China3 cities47.0
- 3India5 cities46.7
- 4Poland71 cities25.8
- 5Thailand14 cities, was 7225.6
- 6Serbia14 cities23.3
- 7Taiwan43 cities20.5
- 8Chile42 cities19.0
- 9Mexico12 cities16.2
- 10Bulgaria4 cities15.7
- 11Hungary3 cities, was 913.3
- 12Singapore6 cities12.4
- 13Brazil32 cities9.0
- 14Japan500 cities8.2
- 15Norway18 cities8.2
- 16United Kingdom49 cities8.0
- 17Australia23 cities7.0
- 18United States780 cities5.7
- 19Canada112 cities5.0
- 20Iceland4 cities3.4
Not counted on this day, too few cities measured: Hong Kong since 26 Mar 2024, Montenegro since 26 Mar 2024, Peru since 24 Mar 2024 and 22 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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.