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 29 May 2025: Chile 41.8 µg/m³, Peru 34.2 µg/m³ and India 29.0 µg/m³.
- 1Chile46 cities41.8
- 2Peru3 cities34.2
- 3India102 cities29.0
- 4South Korea140 cities18.6
- 5Mexico47 cities18.2
- 6Hong Kong13 cities15.2
- 7New Zealand6 cities13.3
- 8Taiwan45 cities10.7
- 9Thailand79 cities10.3
- 10Greece8 cities10.2
- 11Malta4 cities10.2
- 12Latvia4 cities9.3
- 13Serbia38 cities8.9
- 14Laos3 cities8.6
- 15Poland73 cities8.2
- 16Italy18 cities, was 268.0
- 17Japan556 cities7.8
- 18Spain117 cities7.6
- 19Slovakia42 cities6.7
- 20Hungary11 cities6.4
+ 23 more countries, 6.3 µg/m³ and below
- 31United States822 cities4.9
Not counted on this day, too few cities measured: Lithuania since 20 May 2025, Martinique since 16 May 2025 and Luxembourg since 21 Apr 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.