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 18 Aug 2023: Chile 38.8 µg/m³, Pakistan 32.7 µg/m³ and India 26.5 µg/m³.
- 1Chile44 cities38.8
- 2Pakistan4 cities32.7
- 3India5 cities26.5
- 4China3 cities22.2
- 5Peru4 cities21.1
- 6Malta4 cities16.3
- 7Mexico39 cities, was 1114.5
- 8Thailand11 cities13.9
- 9Singapore5 cities12.9
- 10Greece7 cities12.6
- 11Martinique3 cities12.6
- 12Serbia3 cities11.3
- 13Italy4 cities, was 2610.1
- 14Hong Kong12 cities9.9
- 15Romania7 cities9.8
- 16North Macedonia7 cities9.7
- 17Canada112 cities9.0
- 18Slovakia27 cities9.0
- 19Czechia30 cities8.9
- 20United States754 cities8.9
+ 16 more countries, 8.7 µg/m³ and below
Not counted on this day, too few cities measured: Reunion since 16 Aug 2023, Lithuania since 27 Jul 2023 and Luxembourg since 27 Jul 2023.
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.