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 21 Dec 2024: Pakistan 136.6 µg/m³, India 121.6 µg/m³ and Bosnia and Herzegovina 68.7 µg/m³.
- 1Pakistan3 cities136.6
- 2India4 cities121.6
- 3Bosnia and Herzegovina4 cities68.7
- 4Serbia25 cities40.1
- 5China3 cities33.7
- 6Thailand16 cities28.1
- 7Hong Kong13 cities23.5
- 8Slovenia11 cities20.9
- 9Romania9 cities20.2
- 10Bulgaria8 cities20.1
- 11Croatia6 cities18.9
- 12Peru18 cities18.7
- 13Chile46 cities18.2
- 14Poland72 cities18.0
- 15Hungary11 cities17.9
- 16Mexico11 cities16.7
- 17Greece9 cities16.3
- 18Slovakia38 cities15.1
- 19South Korea141 cities14.7
- 20Taiwan43 cities13.1
+ 24 more countries, the next at 11.8 µg/m³
- 35United States817 cities7.0
Not counted on this day, too few cities measured: France since 19 Dec 2024, 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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.