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 30 Dec 2024: Pakistan 175.6 µg/m³, India 119.9 µg/m³ and Bosnia and Herzegovina 62.0 µg/m³.
- 1Pakistan3 cities175.6
- 2India4 cities119.9
- 3Bosnia and Herzegovina3 cities62.0
- 4Serbia23 cities39.7
- 5China4 cities37.4
- 6Thailand16 cities32.6
- 7Hong Kong13 cities30.3
- 8Slovenia12 cities24.7
- 9Hungary11 cities22.4
- 10Poland70 cities21.6
- 11Croatia5 cities19.7
- 12Peru17 cities18.6
- 13Bulgaria8 cities18.5
- 14Mexico12 cities18.4
- 15Chile46 cities18.1
- 16Slovakia40 cities17.3
- 17Czechia37 cities16.5
- 18South Korea141 cities15.9
- 19Romania9 cities15.2
- 20Greece7 cities15.0
+ 25 more countries, 14.2 µg/m³ and below
- 33United States824 cities7.4
Not counted on this day, too few cities measured: 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.