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 20 Sep 2024: Pakistan 40.6 µg/m³, Chile 30.8 µg/m³ and Peru 24.2 µg/m³.
- 1Pakistan4 cities40.6
- 2Chile45 cities30.8
- 3Peru14 cities24.2
- 4China3 cities21.6
- 5India5 cities21.0
- 6Hungary4 cities16.4
- 7Singapore5 cities15.2
- 8Poland71 cities14.8
- 9Serbia10 cities14.5
- 10Thailand14 cities13.4
- 11Hong Kong13 cities12.3
- 12Taiwan43 cities11.7
- 13South Korea141 cities11.3
- 14The Netherlands20 cities8.7
- 15United Kingdom64 cities7.7
- 16Japan547 cities7.5
- 17Bulgaria5 cities7.2
- 18United States814 cities7.1
- 19Canada120 cities6.7
- 20Australia35 cities6.3
+ 3 more countries, 6.3 µg/m³ and below
Not counted on this day, too few cities measured: Mexico since 15 Sep 2024, Belgium since 24 Aug 2024, Switzerland since 24 Aug 2024 and 21 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.