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 23 Dec 2024: Pakistan 142.5 µg/m³, India 119.0 µg/m³ and Bosnia and Herzegovina 64.7 µg/m³.
- 1Pakistan3 cities142.5
- 2India4 cities119.0
- 3Bosnia and Herzegovina3 cities64.7
- 4Serbia25 cities41.4
- 5China3 cities35.4
- 6Thailand16 cities29.2
- 7Hong Kong13 cities24.7
- 8Bulgaria8 cities21.4
- 9Slovenia11 cities20.8
- 10Romania9 cities20.5
- 11Croatia6 cities19.1
- 12Peru18 cities18.8
- 13Hungary11 cities18.2
- 14Chile46 cities18.0
- 15Poland72 cities17.8
- 16Mexico10 cities17.2
- 17Greece9 cities16.6
- 18Slovakia39 cities14.6
- 19South Korea141 cities14.4
- 20Taiwan43 cities13.4
+ 23 more countries, 11.6 µg/m³ and below
- 32United States822 cities7.1
Not counted on this day, too few cities measured: France since 19 Dec 2024, Martinique since 18 Dec 2024 and Luxembourg since 7 Dec 2024.
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.