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 8 Aug 2025: Chile 36.8 µg/m³, Pakistan 31.6 µg/m³ and Ghana 27.8 µg/m³.
- 1Chile47 cities36.8
- 2Pakistan11 cities31.6
- 3Ghana3 cities27.8
- 4Peru5 cities26.3
- 5Philippines3 cities23.7
- 6India228 cities23.2
- 7Brazil3 cities14.6
- 8New Zealand10 cities13.9
- 9South Korea141 cities13.3
- 10Japan563 cities12.5
- 11Hong Kong13 cities11.3
- 12Canada114 cities10.7
- 13Mexico37 cities10.2
- 14Italy26 cities9.8
- 15Spain109 cities9.7
- 16Romania11 cities9.5
- 17Greece10 cities9.1
- 18Martinique3 cities9.1
- 19United States845 cities8.9
- 20Bosnia and Herzegovina5 cities8.1
+ 26 more countries, 7.8 µg/m³ and below
Not counted on this day, too few cities measured: China since 7 Aug 2025, 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.