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 23 Mar 2024: Pakistan 53.3 µg/m³, India 43.7 µg/m³ and China 35.9 µg/m³.
- 1Pakistan4 cities53.3
- 2India4 cities43.7
- 3China4 cities35.9
- 4Serbia10 cities31.4
- 5Thailand11 cities, was 7831.0
- 6Taiwan43 cities22.1
- 7Poland74 cities20.8
- 8Chile45 cities19.9
- 9Singapore5 cities12.8
- 10Mexico11 cities12.6
- 11Bulgaria5 cities12.1
- 12Japan504 cities9.1
- 13United Kingdom4 cities, was 596.5
- 14Norway18 cities6.0
- 15United States769 cities5.2
- 16Canada107 cities4.1
Not counted on this day, too few cities measured: Peru since 23 Mar 2024, Australia since 22 Mar 2024, Hong Kong since 22 Mar 2024 and 27 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.