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 1 Apr 2023: China 43.4 µg/m³, Pakistan 34.7 µg/m³ and Mexico 25.7 µg/m³.
- 1China4 cities43.4
- 2Pakistan4 cities34.7
- 3Mexico49 cities25.7
- 4Thailand77 cities25.1
- 5Chile45 cities24.6
- 6Peru5 cities15.6
- 7South Africa11 cities15.5
- 8Hong Kong12 cities12.2
- 9Greece8 cities11.5
- 10Poland64 cities11.5
- 11Romania7 cities11.1
- 12Brazil34 cities11.0
- 13Slovakia24 cities9.5
- 14Czechia22 cities9.3
- 15Italy19 cities9.3
- 16Singapore6 cities9.1
- 17Bulgaria7 cities8.8
- 18Spain87 cities8.4
- 19Ireland4 cities7.7
- 20Hungary7 cities7.4
+ 15 more countries, the next at 6.9 µg/m³
- 21United States688 cities6.9
Not counted on this day, too few cities measured: Sweden since 29 Mar 2023, Kosovo since 28 Mar 2023, Bosnia and Herzegovina since 22 Mar 2023 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, 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.