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 17 Feb 2025: India 82.2 µg/m³, Pakistan 71.3 µg/m³ and Bosnia and Herzegovina 54.3 µg/m³.
- 1India5 cities82.2
- 2Pakistan4 cities71.3
- 3Bosnia and Herzegovina4 cities54.3
- 4Thailand83 cities, was 1642.1
- 5China3 cities39.4
- 6Serbia39 cities37.1
- 7Poland76 cities34.9
- 8Laos3 cities31.5
- 9Slovenia12 cities29.9
- 10Romania10 cities28.6
- 11Bulgaria8 cities27.5
- 12Hungary12 cities26.3
- 13Czechia37 cities, was 3726.0
- 14Belgium45 cities25.2
- 15Hong Kong11 cities24.9
- 16The Netherlands24 cities24.9
- 17South Korea141 cities24.2
- 18Slovakia40 cities22.7
- 19United Kingdom5 cities22.3
- 20Switzerland10 cities, was 1021.9
+ 23 more countries, 21.4 µg/m³ and below
- 35United States825 cities6.7
Not counted on this day, too few cities measured: Ireland since 16 Feb 2025, Lithuania since 16 Feb 2025, Martinique since 15 Feb 2025 and 2 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.