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 10 Jan 2025: Pakistan 107.6 µg/m³, India 92.3 µg/m³ and Thailand 46.9 µg/m³.
- 1Pakistan4 cities107.6
- 2India5 cities92.3
- 3Thailand16 cities46.9
- 4China4 cities44.9
- 5Serbia25 cities31.0
- 6Hong Kong13 cities30.9
- 7Romania10 cities30.2
- 8Bulgaria8 cities29.1
- 9Greece7 cities23.1
- 10Croatia5 cities18.8
- 11Mexico16 cities17.5
- 12Chile44 cities17.1
- 13Poland72 cities16.8
- 14South Korea141 cities15.9
- 15Taiwan43 cities15.9
- 16Slovakia41 cities13.5
- 17Peru5 cities, was 1613.4
- 18Czechia36 cities13.3
- 19Hungary12 cities13.0
- 20Ireland7 cities12.8
+ 23 more countries, 11.9 µg/m³ and below
- 34United States822 cities6.3
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 10 Jan 2025, Martinique since 10 Jan 2025, Singapore since 9 Jan 2025 and 3 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.