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 25 Apr 2024: Laos 56.9 µg/m³, India 46.3 µg/m³ and China 37.1 µg/m³.
- 1Laos3 cities56.9
- 2India5 cities46.3
- 3China4 cities37.1
- 4Thailand84 cities, was 1333.4
- 5Chile46 cities28.7
- 6Pakistan3 cities28.7
- 7Peru12 cities22.4
- 8Taiwan43 cities19.6
- 9Mexico18 cities18.0
- 10Serbia24 cities17.8
- 11Brazil21 cities16.7
- 12Greece8 cities16.1
- 13South Korea141 cities15.9
- 14Bosnia and Herzegovina4 cities14.8
- 15Poland71 cities13.6
- 16Singapore6 cities13.3
- 17Japan516 cities12.6
- 18Hong Kong12 cities12.5
- 19Croatia4 cities9.5
- 20New Zealand5 cities8.8
+ 25 more countries, the next at 8.2 µg/m³
- 38United States792 cities5.3
Not counted on this day, too few cities measured: North Macedonia since 25 Apr 2024, Malta since 25 Apr 2024, Sweden since 25 Apr 2024 and 6 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.