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 28 Sep 2023: Pakistan 56.0 µg/m³, China 30.4 µg/m³ and Peru 25.7 µg/m³.
- 1Pakistan3 cities56.0
- 2China3 cities30.4
- 3Peru5 cities25.7
- 4India4 cities24.4
- 5Chile44 cities20.8
- 6Greece7 cities19.7
- 7Brazil29 cities17.5
- 8Thailand10 cities16.3
- 9Singapore6 cities16.2
- 10Mexico41 cities15.1
- 11Serbia3 cities12.9
- 12Malta4 cities12.5
- 13Poland53 cities11.6
- 14Czechia35 cities11.4
- 15Hungary10 cities11.0
- 16Hong Kong13 cities10.2
- 17Romania6 cities10.1
- 18Slovakia27 cities9.7
- 19Canada117 cities9.4
- 20Italy28 cities9.4
+ 16 more countries, the next at 8.2 µg/m³
- 26United States758 cities7.1
Not counted on this day, too few cities measured: Reunion since 26 Sep 2023, North Macedonia since 16 Sep 2023, Lithuania since 11 Sep 2023 and Luxembourg since 6 Sep 2023.
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.