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 29 Jun 2023: Pakistan 38.9 µg/m³, Chile 28.6 µg/m³ and China 22.2 µg/m³.
- 1Pakistan4 cities38.9
- 2Chile46 cities28.6
- 3China3 cities22.2
- 4India5 cities18.0
- 5Malta4 cities14.3
- 6Mexico16 cities13.7
- 7Thailand10 cities12.9
- 8Greece8 cities11.9
- 9Italy27 cities10.6
- 10Singapore5 cities10.4
- 11Slovakia26 cities10.2
- 12Belgium41 cities10.1
- 13Spain93 cities9.7
- 14United States738 cities9.6
- 15Hungary7 cities9.4
- 16Bulgaria6 cities9.2
- 17Czechia34 cities9.1
- 18Romania5 cities9.1
- 19Canada109 cities8.6
- 20Martinique3 cities8.5
+ 12 more countries, 8.5 µg/m³ and below
Not counted on this day, too few cities measured: Luxembourg since 24 Jun 2023, The Netherlands since 24 Jun 2023, Poland since 24 Jun 2023 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.