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 22 May 2025: Chile 41.2 µg/m³, Peru 35.8 µg/m³ and India 27.3 µg/m³.
- 1Chile45 cities41.2
- 2Peru6 cities35.8
- 3India207 cities27.3
- 4Mexico44 cities27.3
- 5Thailand78 cities13.8
- 6New Zealand6 cities13.3
- 7Japan567 cities12.7
- 8Malta3 cities12.6
- 9South Korea140 cities12.3
- 10Serbia39 cities10.8
- 11United Kingdom69 cities9.2
- 12Belgium45 cities8.9
- 13Taiwan45 cities8.8
- 14Latvia4 cities8.5
- 15Poland72 cities8.5
- 16Laos3 cities8.2
- 17Hong Kong13 cities7.4
- 18Hungary11 cities7.4
- 19The Netherlands34 cities7.0
- 20Spain82 cities, was 1116.9
+ 17 more countries, 6.9 µg/m³ and below
- 30United States823 cities5.0
Not counted on this day, too few cities measured: France since 20 May 2025, Lithuania since 20 May 2025, Estonia since 19 May 2025 and 6 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.