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 21 Feb 2025: India 61.5 µg/m³, Pakistan 57.0 µg/m³ and Serbia 43.8 µg/m³.
- 1India5 cities61.5
- 2Pakistan3 cities57.0
- 3Serbia39 cities43.8
- 4Bosnia and Herzegovina4 cities38.5
- 5Poland74 cities36.4
- 6Thailand86 cities, was 1634.5
- 7Slovenia12 cities30.0
- 8Laos3 cities28.1
- 9Hong Kong11 cities27.6
- 10Romania10 cities26.9
- 11Switzerland10 cities, was 1026.4
- 12Hungary12 cities26.1
- 13Czechia30 cities, was 3725.3
- 14China3 cities23.2
- 15Bulgaria8 cities23.1
- 16Slovakia41 cities22.8
- 17France109 cities22.2
- 18Belgium45 cities20.2
- 19United Kingdom6 cities20.2
- 20Chile41 cities19.3
+ 25 more countries, 19.2 µg/m³ and below
- 38United States808 cities6.0
Not counted on this day, too few cities measured: Lithuania since 16 Feb 2025, Martinique since 15 Feb 2025 and Singapore since 9 Jan 2025.
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.