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 20 Jan 2025: Pakistan 119.7 µg/m³, India 103.7 µg/m³ and Thailand 46.2 µg/m³.
- 1Pakistan4 cities119.7
- 2India5 cities103.7
- 3Thailand16 cities46.2
- 4Bulgaria5 cities39.4
- 5Serbia10 cities37.5
- 6China4 cities36.5
- 7Slovenia12 cities30.8
- 8Romania9 cities29.4
- 9Hong Kong13 cities28.9
- 10Belgium45 cities26.5
- 11South Korea141 cities26.4
- 12France25 cities, was 10525.9
- 13Poland72 cities25.2
- 14Hungary9 cities24.7
- 15Slovakia42 cities23.0
- 16Switzerland9 cities21.0
- 17The Netherlands23 cities20.8
- 18Luxembourg3 cities20.2
- 19Mexico12 cities19.1
- 20Taiwan43 cities18.0
+ 19 more countries, the next at 17.3 µg/m³
- 31United States799 cities7.3
Not counted on this day, too few cities measured: Estonia since 17 Jan 2025, Ireland since 17 Jan 2025, Greece since 16 Jan 2025 and 8 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.