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 22 Sep 2023: Pakistan 38.8 µg/m³, Chile 27.0 µg/m³ and Peru 26.3 µg/m³.
- 1Pakistan4 cities38.8
- 2Chile43 cities27.0
- 3Peru4 cities26.3
- 4India5 cities22.7
- 5China3 cities21.5
- 6Mexico43 cities15.3
- 7Singapore5 cities14.3
- 8Thailand11 cities13.3
- 9Greece7 cities13.0
- 10Serbia3 cities13.0
- 11Malta4 cities12.9
- 12Poland48 cities12.1
- 13Czechia35 cities11.1
- 14Hungary9 cities11.1
- 15Italy27 cities10.5
- 16Slovakia27 cities10.2
- 17Bulgaria6 cities9.8
- 18Hong Kong11 cities9.5
- 19Belgium41 cities9.2
- 20Martinique3 cities9.2
+ 15 more countries, 8.5 µg/m³ and below
- 25United States762 cities8.1
Not counted on this day, too few cities measured: North Macedonia since 20 Sep 2023, Reunion since 16 Aug 2023, Lithuania since 27 Jul 2023 and Luxembourg since 27 Jul 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.