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 22 Oct 2024: Pakistan 86.0 µg/m³, China 27.6 µg/m³ and India 26.9 µg/m³.
- 1Pakistan3 cities86.0
- 2China3 cities27.6
- 3India5 cities26.9
- 4Chile46 cities21.1
- 5Peru16 cities19.7
- 6Brazil35 cities18.1
- 7Thailand16 cities17.5
- 8Serbia21 cities16.2
- 9Hong Kong13 cities16.0
- 10Hungary4 cities15.5
- 11Singapore6 cities13.1
- 12Poland73 cities12.4
- 13South Korea140 cities9.8
- 14Taiwan43 cities9.8
- 15Bulgaria5 cities6.8
- 16Japan552 cities6.7
- 17United States803 cities6.6
- 18Norway17 cities6.3
- 19Australia55 cities5.8
- 20New Zealand7 cities5.7
+ 4 more countries, the next at 5.6 µg/m³
Not counted on this day, too few cities measured: Mexico since 26 Sep 2024, Belgium since 24 Aug 2024, Switzerland since 24 Aug 2024 and 10 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, 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.