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 21 Mar 2025: India 35.7 µg/m³, Thailand 28.9 µg/m³ and Laos 27.9 µg/m³.
- 1India230 cities, was 535.7
- 2Thailand86 cities28.9
- 3Laos3 cities27.9
- 4Serbia39 cities, was 1227.8
- 5Mexico55 cities, was 1423.4
- 6Poland73 cities22.1
- 7South Korea141 cities22.0
- 8Chile45 cities20.2
- 9Hong Kong13 cities18.8
- 10Peru6 cities18.7
- 11Taiwan44 cities16.7
- 12Greece13 cities16.2
- 13Ireland5 cities15.6
- 14Romania10 cities14.8
- 15Hungary4 cities13.7
- 16United Kingdom7 cities13.6
- 17Slovakia42 cities12.8
- 18Latvia4 cities11.7
- 19Germany235 cities11.2
- 20France107 cities, was 2311.2
+ 22 more countries, the next at 11.2 µg/m³
- 35United States840 cities5.8
Not counted on this day, too few cities measured: Lithuania since 20 Mar 2025, Bosnia and Herzegovina since 18 Mar 2025, Croatia since 14 Mar 2025 and 4 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.