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 25 Aug 2023: Pakistan 43.8 µg/m³, India 22.8 µg/m³ and Chile 22.6 µg/m³.
- 1Pakistan4 cities43.8
- 2India5 cities22.8
- 3Chile43 cities22.6
- 4China3 cities22.3
- 5Malta4 cities21.1
- 6Slovakia25 cities16.8
- 7Serbia3 cities16.6
- 8Greece7 cities16.2
- 9Czechia34 cities15.9
- 10Thailand11 cities15.4
- 11Italy17 cities15.3
- 12Switzerland8 cities14.1
- 13Hungary7 cities14.0
- 14North Macedonia7 cities14.0
- 15Romania6 cities12.9
- 16Bulgaria6 cities12.4
- 17United States753 cities11.6
- 18Canada118 cities11.5
- 19Austria30 cities11.3
- 20Mexico12 cities11.2
+ 11 more countries, 11.2 µg/m³ and below
Not counted on this day, too few cities measured: Martinique since 22 Aug 2023, Australia since 21 Aug 2023, Hong Kong since 21 Aug 2023 and 5 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.