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 6 Aug 2025: Chile 32.5 µg/m³, Pakistan 32.0 µg/m³ and Peru 29.6 µg/m³.
- 1Chile47 cities32.5
- 2Pakistan11 cities32.0
- 3Peru5 cities29.6
- 4Philippines3 cities26.8
- 5Ghana3 cities25.0
- 6India224 cities22.7
- 7China3 cities16.8
- 8South Korea141 cities14.8
- 9New Zealand10 cities14.7
- 10Japan565 cities12.7
- 11Brazil3 cities11.7
- 12Canada115 cities11.3
- 13Hong Kong13 cities11.0
- 14Mexico41 cities10.9
- 15Martinique3 cities10.1
- 16Romania11 cities9.5
- 17United States846 cities9.4
- 18Greece11 cities8.9
- 19Italy27 cities8.8
- 20Bulgaria8 cities8.3
+ 27 more countries, 8.2 µg/m³ and below
Not counted on this day, too few cities measured: Serbia since 3 Jul 2025, Thailand since 3 Jul 2025 and Taiwan since 3 Jul 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.