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 8 Apr 2023: Laos 105.1 µg/m³, India 42.5 µg/m³ and Thailand 36.6 µg/m³.
- 1Laos3 cities105.1
- 2India3 cities42.5
- 3Thailand77 cities36.6
- 4China4 cities31.6
- 5Pakistan4 cities31.4
- 6Serbia21 cities24.8
- 7Chile45 cities24.4
- 8Mexico45 cities24.2
- 9South Africa9 cities20.0
- 10Hong Kong12 cities14.8
- 11Czechia30 cities13.0
- 12Bulgaria6 cities12.2
- 13Romania7 cities12.1
- 14Greece8 cities12.0
- 15Poland64 cities11.9
- 16Belgium37 cities11.6
- 17Hungary8 cities11.3
- 18Italy19 cities10.9
- 19Slovakia25 cities10.4
- 20The Netherlands31 cities9.3
+ 16 more countries, 9.1 µg/m³ and below
- 30United States686 cities6.2
Not counted on this day, too few cities measured: Singapore since 8 Apr 2023, Brazil since 7 Apr 2023, Peru since 6 Apr 2023 and 7 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 and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.