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 21 Jun 2025: Pakistan 53.7 µg/m³, Chile 40.4 µg/m³ and Peru 24.1 µg/m³.
- 1Pakistan6 cities53.7
- 2Chile43 cities40.4
- 3Peru6 cities24.1
- 4India210 cities21.6
- 5New Zealand10 cities18.7
- 6South Korea140 cities13.7
- 7Serbia39 cities12.6
- 8Japan566 cities10.9
- 9Hungary4 cities, was 410.4
- 10Mexico45 cities9.7
- 11Bulgaria5 cities9.6
- 12Thailand75 cities9.6
- 13Poland72 cities8.7
- 14Austria36 cities8.5
- 15United Kingdom65 cities7.5
- 16Hong Kong12 cities7.3
- 17Taiwan45 cities6.7
- 18United States822 cities6.7
- 19The Netherlands22 cities6.5
- 20Canada116 cities6.1
+ 4 more countries, 6.0 µg/m³ and below
Not counted on this day, too few cities measured: Spain since 17 Jun 2025, Latvia since 17 Jun 2025, Romania since 17 Jun 2025 and 20 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.