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 31 May 2023: Chile 45.2 µg/m³, Pakistan 33.0 µg/m³ and China 31.5 µg/m³.
- 1Chile46 cities45.2
- 2Pakistan4 cities33.0
- 3China3 cities31.5
- 4India5 cities29.1
- 5Thailand10 cities, was 7721.6
- 6Mexico12 cities, was 4719.3
- 7Serbia3 cities, was 2114.1
- 8Slovakia26 cities13.8
- 9Malta3 cities12.9
- 10Italy25 cities11.6
- 11Brazil32 cities11.5
- 12Greece7 cities11.2
- 13Hungary8 cities10.8
- 14Czechia35 cities10.6
- 15France130 cities10.1
- 16Switzerland9 cities9.8
- 17Belgium38 cities9.7
- 18Singapore6 cities9.1
- 19Spain97 cities8.6
- 20Austria30 cities8.5
+ 13 more countries, the next at 8.4 µg/m³
- 28United States726 cities7.2
Not counted on this day, too few cities measured: Romania since 31 May 2023, Poland since 29 May 2023, Luxembourg since 28 May 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.