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 30 days to 15 Sep 2024: Pakistan 36.6 µg/m³, Chile 33.7 µg/m³ and Peru 25.9 µg/m³.
- 1Pakistan4 cities36.6
- 2Chile45 cities33.7
- 3Peru13 cities25.9
- 4China3 cities21.4
- 5India5 cities20.5
- 6Hungary4 cities16.7
- 7Serbia10 cities14.3
- 8Singapore5 cities14.3
- 9Thailand15 cities13.6
- 10Poland72 cities12.9
- 11Hong Kong13 cities11.9
- 12South Korea141 cities11.8
- 13Taiwan43 cities11.0
- 14Japan550 cities7.6
- 15The Netherlands20 cities7.5
- 16New Zealand5 cities7.5
- 17United Kingdom62 cities7.4
- 18Bulgaria5 cities7.3
- 19United States812 cities7.3
- 20Canada119 cities6.6
+ 3 more countries, 6.5 µg/m³ and below
Not counted on this day, too few cities measured: Mexico since 15 Sep 2024, Belgium since 24 Aug 2024, Switzerland since 24 Aug 2024 and 22 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.