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 16 Jul 2025: Chile 45.6 µg/m³, Pakistan 33.3 µg/m³ and Peru 28.5 µg/m³.
- 1Chile47 cities45.6
- 2Pakistan11 cities33.3
- 3Peru5 cities28.5
- 4India217 cities21.2
- 5Mexico47 cities16.0
- 6New Zealand10 cities13.4
- 7Martinique3 cities13.0
- 8Canada115 cities11.2
- 9South Korea140 cities10.8
- 10Hong Kong13 cities9.8
- 11Italy21 cities, was 99.7
- 12Finland15 cities9.6
- 13Spain119 cities8.7
- 14Norway20 cities8.6
- 15Romania11 cities8.5
- 16Japan555 cities8.3
- 17Sweden14 cities8.3
- 18Slovakia41 cities8.3
- 19Lithuania4 cities7.8
- 20Greece8 cities7.7
+ 20 more countries, 7.5 µg/m³ and below
- 22United States848 cities7.5
Not counted on this day, too few cities measured: Ireland since 14 Jul 2025, Luxembourg since 10 Jul 2025, Czechia since 3 Jul 2025 and 5 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.