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 30 days to 22 Jan 2025: Pakistan 153.6 µg/m³, India 97.4 µg/m³ and China 44.1 µg/m³.
- 1Pakistan3 cities153.6
- 2India5 cities97.4
- 3China4 cities44.1
- 4Thailand16 cities43.3
- 5Serbia10 cities35.7
- 6Bulgaria5 cities33.8
- 7Hong Kong13 cities31.2
- 8Slovenia12 cities26.5
- 9Romania10 cities24.4
- 10Poland65 cities24.0
- 11South Korea141 cities22.7
- 12Hungary9 cities22.0
- 13Slovakia42 cities20.9
- 14Mexico13 cities19.3
- 15Chile45 cities17.2
- 16Taiwan43 cities17.0
- 17Peru5 cities, was 1515.8
- 18Austria36 cities15.7
- 19Belgium45 cities14.8
- 20Greece5 cities14.3
+ 21 more countries, 14.2 µg/m³ and below
- 33United States823 cities7.2
Not counted on this day, too few cities measured: Czechia since 18 Jan 2025, Singapore since 16 Jan 2025, Croatia since 15 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.