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 26 Sep 2023: Pakistan 47.2 µg/m³, China 26.5 µg/m³ and Peru 26.0 µg/m³.
- 1Pakistan3 cities47.2
- 2China3 cities26.5
- 3Peru4 cities26.0
- 4Chile44 cities21.4
- 5Greece7 cities20.7
- 6Thailand11 cities18.8
- 7India4 cities18.6
- 8Mexico43 cities15.1
- 9Malta4 cities14.0
- 10Serbia3 cities14.0
- 11Singapore5 cities13.3
- 12Hong Kong13 cities9.5
- 13Czechia35 cities9.3
- 14Canada117 cities9.1
- 15Hungary9 cities9.1
- 16Romania6 cities9.1
- 17Poland48 cities8.9
- 18Bulgaria5 cities8.2
- 19Slovakia27 cities7.8
- 20Italy27 cities7.4
+ 15 more countries, 7.3 µg/m³ and below
- 22United States765 cities7.3
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 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.