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 30 days to 27 Aug 2023: Pakistan 37.6 µg/m³, Chile 35.5 µg/m³ and India 27.7 µg/m³.
- 1Pakistan4 cities37.6
- 2Chile44 cities35.5
- 3India5 cities27.7
- 4Peru3 cities24.8
- 5China3 cities23.1
- 6Malta4 cities15.3
- 7Mexico36 cities, was 1114.1
- 8Thailand11 cities14.1
- 9Greece7 cities12.7
- 10Serbia3 cities12.2
- 11Singapore5 cities12.2
- 12Czechia26 cities10.7
- 13Slovakia27 cities10.7
- 14Canada113 cities10.6
- 15Italy3 cities10.5
- 16Romania6 cities10.5
- 17Hungary7 cities10.1
- 18Bulgaria6 cities9.9
- 19North Macedonia7 cities9.9
- 20Hong Kong12 cities9.4
+ 14 more countries, 9.3 µg/m³ and below
- 21United States761 cities9.3
Not counted on this day, too few cities measured: Martinique since 22 Aug 2023, Poland since 21 Aug 2023, Reunion since 16 Aug 2023 and 2 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.