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 Aug 2023: Pakistan 37.2 µg/m³, Chile 29.0 µg/m³ and India 25.8 µg/m³.
- 1Pakistan4 cities37.2
- 2Chile41 cities29.0
- 3India5 cities25.8
- 4China3 cities14.9
- 5Mexico43 cities13.5
- 6Thailand11 cities12.4
- 7Singapore5 cities12.2
- 8Bulgaria4 cities11.3
- 9United States754 cities10.0
- 10Canada116 cities9.8
- 11Japan509 cities5.6
- 12United Kingdom3 cities5.0
Not counted on this day, too few cities measured: Austria since 27 Aug 2023, Belgium since 27 Aug 2023, Switzerland since 27 Aug 2023 and 24 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 and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.