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 23 Dec 2024: Pakistan 249.6 µg/m³, India 124.3 µg/m³ and Serbia 56.7 µg/m³.
- 1Pakistan3 cities249.6
- 2India4 cities124.3
- 3Serbia25 cities56.7
- 4China3 cities39.8
- 5Thailand16 cities33.2
- 6Hong Kong12 cities32.4
- 7Croatia5 cities24.6
- 8Bulgaria8 cities23.6
- 9Romania10 cities22.5
- 10Slovenia12 cities18.6
- 11Peru17 cities17.8
- 12Greece9 cities17.7
- 13Chile45 cities17.6
- 14South Korea141 cities17.0
- 15Hungary11 cities15.4
- 16Slovakia41 cities13.1
- 17Taiwan43 cities13.0
- 18Mexico11 cities11.2
- 19Poland70 cities11.2
- 20Singapore5 cities11.0
+ 23 more countries, 10.3 µg/m³ and below
- 29United States825 cities6.9
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 22 Dec 2024, France since 18 Dec 2024, Martinique since 18 Dec 2024 and 4 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.