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 20 Dec 2024: Pakistan 203.4 µg/m³, India 128.5 µg/m³ and Bosnia and Herzegovina 115.1 µg/m³.
- 1Pakistan3 cities203.4
- 2India4 cities128.5
- 3Bosnia and Herzegovina3 cities115.1
- 4Serbia25 cities60.2
- 5China4 cities34.1
- 6Hong Kong13 cities29.9
- 7Slovenia12 cities27.7
- 8Thailand16 cities26.3
- 9Croatia6 cities23.8
- 10Romania10 cities22.2
- 11Bulgaria8 cities21.2
- 12Chile46 cities18.3
- 13Greece9 cities18.2
- 14Taiwan43 cities18.0
- 15Peru18 cities17.6
- 16Hungary11 cities17.3
- 17Mexico13 cities17.0
- 18South Korea141 cities15.0
- 19Slovakia42 cities13.1
- 20Spain115 cities12.1
+ 24 more countries, 11.2 µg/m³ and below
- 32United States820 cities6.9
Not counted on this day, too few cities measured: France since 18 Dec 2024, Martinique since 18 Dec 2024, Puerto Rico since 7 Dec 2024 and 3 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.