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 May 2023: China 33.0 µg/m³, Pakistan 32.3 µg/m³ and Chile 30.1 µg/m³.
- 1China4 cities33.0
- 2Pakistan3 cities32.3
- 3Chile41 cities30.1
- 4Thailand9 cities24.6
- 5Mexico38 cities22.8
- 6Czechia30 cities12.9
- 7Belgium37 cities12.4
- 8Greece9 cities11.9
- 9United Kingdom5 cities11.6
- 10Poland58 cities11.5
- 11Slovakia24 cities10.8
- 12Brazil33 cities10.4
- 13Hungary8 cities10.0
- 14Austria23 cities9.0
- 15Romania7 cities9.0
- 16Singapore6 cities8.9
- 17Malta3 cities8.6
- 18Germany182 cities8.3
- 19Italy23 cities8.3
- 20Bulgaria7 cities8.1
+ 13 more countries, the next at 7.8 µg/m³
- 25United States684 cities6.6
Not counted on this day, too few cities measured: India since 1 May 2023, Luxembourg since 25 Apr 2023, Serbia since 24 Apr 2023 and 11 more countries. Days missing from the source archive fall in this window, so fewer countries are counted.
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.