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 18 Jun 2024: China 28.7 µg/m³, Chile 25.2 µg/m³ and India 24.2 µg/m³.
- 1China4 cities28.7
- 2Chile42 cities25.2
- 3India4 cities24.2
- 4Peru13 cities21.6
- 5South Korea140 cities16.3
- 6New Zealand5 cities14.1
- 7Greece7 cities13.5
- 8Malta5 cities12.3
- 9Singapore5 cities12.2
- 10Mexico4 cities, was 1212.0
- 11Serbia18 cities11.7
- 12Thailand66 cities11.5
- 13Japan559 cities10.1
- 14North Macedonia8 cities9.5
- 15Slovakia39 cities8.8
- 16Poland73 cities8.2
- 17Taiwan43 cities8.2
- 18Hong Kong12 cities, was 118.1
- 19United States796 cities7.8
- 20Bulgaria8 cities7.7
+ 21 more countries, 7.7 µg/m³ and below
Not counted on this day, too few cities measured: Pakistan since 18 Jun 2024, Switzerland since 6 Jun 2024, Iceland since 6 Jun 2024 and 7 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.