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 18 Dec 2024: Pakistan 191.3 µg/m³, India 124.7 µg/m³ and Bosnia and Herzegovina 85.9 µg/m³.
- 1Pakistan3 cities191.3
- 2India4 cities124.7
- 3Bosnia and Herzegovina3 cities85.9
- 4Serbia25 cities48.5
- 5China4 cities28.7
- 6Slovenia12 cities26.7
- 7Hong Kong13 cities25.4
- 8Thailand16 cities25.4
- 9Croatia6 cities22.7
- 10Peru18 cities18.5
- 11Chile47 cities18.1
- 12Hungary11 cities17.8
- 13Taiwan43 cities17.8
- 14Mexico10 cities17.6
- 15Greece9 cities15.7
- 16Romania10 cities15.7
- 17Bulgaria8 cities15.6
- 18Belgium45 cities14.1
- 19Poland73 cities14.1
- 20Slovakia42 cities14.1
+ 24 more countries, 13.4 µg/m³ and below
- 35United States819 cities6.5
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.