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 4 Dec 2025: Pakistan 215.8 µg/m³, India 62.3 µg/m³ and Thailand 32.3 µg/m³.
- 1Pakistan13 cities215.8
- 2India234 cities62.3
- 3Thailand75 cities32.3
- 4Laos3 cities27.7
- 5Peru5 cities27.4
- 6Hong Kong13 cities25.3
- 7Ghana4 cities24.5
- 8Philippines3 cities24.5
- 9Mexico48 cities20.8
- 10Hungary5 cities20.2
- 11Taiwan45 cities17.1
- 12Chile39 cities16.0
- 13Bulgaria4 cities15.9
- 14South Korea129 cities13.3
- 15Japan550 cities9.6
- 16United States841 cities, was 8696.9
- 17The Netherlands17 cities6.6
- 18Canada115 cities, was 1145.5
- 19Australia36 cities5.4
- 20United Kingdom72 cities4.6
+ 2 more countries, 4.1 µg/m³ and below
Not counted on this day, too few cities measured: Serbia since 4 Dec 2025, Senegal since 4 Dec 2025, Austria since 30 Nov 2025 and 28 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.