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 16 Dec 2024: Pakistan 127.7 µg/m³, India 110.4 µg/m³ and Bosnia and Herzegovina 40.4 µg/m³.
- 1Pakistan3 cities127.7
- 2India4 cities110.4
- 3Bosnia and Herzegovina4 cities40.4
- 4Serbia25 cities36.5
- 5China4 cities32.7
- 6Thailand16 cities26.3
- 7Hong Kong13 cities24.3
- 8Slovenia12 cities22.9
- 9Mexico12 cities19.9
- 10Peru17 cities19.0
- 11Chile47 cities18.5
- 12Hungary11 cities17.5
- 13Croatia6 cities17.1
- 14Bulgaria8 cities16.8
- 15South Korea141 cities16.5
- 16Poland73 cities16.0
- 17Belgium45 cities15.2
- 18Taiwan43 cities15.2
- 19France95 cities14.7
- 20Greece9 cities14.6
+ 26 more countries, 14.1 µg/m³ and below
- 37United States820 cities6.7
Not counted on this day, too few cities measured: Puerto Rico since 7 Dec 2024, Luxembourg since 1 Dec 2024, Kosovo since 24 Nov 2024 and Italy since 27 Oct 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.