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 26 Mar 2024: Pakistan 50.3 µg/m³, India 43.0 µg/m³ and China 39.2 µg/m³.
- 1Pakistan4 cities50.3
- 2India5 cities43.0
- 3China4 cities39.2
- 4Thailand72 cities, was 7830.8
- 5Serbia10 cities25.5
- 6Poland75 cities21.5
- 7Taiwan42 cities19.3
- 8Chile41 cities18.6
- 9Mexico11 cities15.0
- 10Singapore6 cities13.4
- 11Bulgaria5 cities9.0
- 12Brazil33 cities7.6
- 13United Kingdom4 cities, was 597.6
- 14Japan475 cities7.6
- 15Australia25 cities5.9
- 16United States775 cities5.3
- 17Norway19 cities5.2
- 18Canada106 cities4.2
Not counted on this day, too few cities measured: Peru since 23 Mar 2024, Hong Kong since 22 Mar 2024, Hungary since 22 Mar 2024 and 26 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.