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 21 Aug 2023: Chile 38.0 µg/m³, Pakistan 35.6 µg/m³ and India 26.8 µg/m³.
- 1Chile44 cities38.0
- 2Pakistan4 cities35.6
- 3India5 cities26.8
- 4Peru3 cities23.7
- 5China3 cities22.9
- 6Malta4 cities15.7
- 7Mexico37 cities, was 1115.0
- 8Thailand11 cities14.2
- 9Singapore5 cities12.6
- 10Greece7 cities12.0
- 11Serbia3 cities11.5
- 12Martinique3 cities11.1
- 13Hong Kong12 cities10.4
- 14Romania7 cities10.4
- 15Italy3 cities, was 269.9
- 16Slovakia27 cities9.8
- 17Czechia30 cities9.7
- 18North Macedonia7 cities9.6
- 19United States755 cities9.4
- 20Canada112 cities9.2
+ 15 more countries, 9.0 µg/m³ and below
Not counted on this day, too few cities measured: Poland since 21 Aug 2023, 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.