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 29 Aug 2023: Pakistan 35.3 µg/m³, Chile 31.9 µg/m³ and India 25.3 µg/m³.
- 1Pakistan4 cities35.3
- 2Chile42 cities31.9
- 3India5 cities25.3
- 4China3 cities14.6
- 5Brazil32 cities13.7
- 6Mexico48 cities13.7
- 7Thailand11 cities12.5
- 8Singapore6 cities12.2
- 9Bulgaria4 cities10.8
- 10Canada116 cities10.3
- 11United States754 cities9.9
- 12Hong Kong12 cities8.4
- 13Australia45 cities7.3
- 14Japan509 cities5.7
- 15United Kingdom27 cities4.2
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 22 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.