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 25 May 2024: Chile 41.6 µg/m³, Pakistan 36.7 µg/m³ and India 35.2 µg/m³.
- 1Chile45 cities41.6
- 2Pakistan4 cities36.7
- 3India5 cities35.2
- 4Laos3 cities33.9
- 5China3 cities25.1
- 6Mexico9 cities23.5
- 7Peru12 cities23.3
- 8Thailand82 cities, was 1523.0
- 9South Korea141 cities15.5
- 10Malta5 cities14.9
- 11Taiwan43 cities14.5
- 12Brazil27 cities14.2
- 13Hong Kong11 cities12.6
- 14New Zealand5 cities12.4
- 15Belgium44 cities11.6
- 16Serbia24 cities10.8
- 17The Netherlands36 cities10.6
- 18Greece7 cities10.3
- 19Poland77 cities10.3
- 20Latvia4 cities10.1
+ 28 more countries, the next at 10.0 µg/m³
- 38United States808 cities6.3
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 2 May 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.