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 Jul 2023: Chile 39.7 µg/m³, Pakistan 37.2 µg/m³ and China 21.8 µg/m³.
- 1Chile46 cities39.7
- 2Pakistan4 cities37.2
- 3China3 cities21.8
- 4India5 cities19.2
- 5Mexico12 cities14.3
- 6Malta4 cities14.0
- 7Thailand11 cities13.1
- 8Greece8 cities12.8
- 9Italy20 cities12.6
- 10Slovakia25 cities12.6
- 11Serbia3 cities11.9
- 12Canada101 cities11.7
- 13Czechia36 cities11.6
- 14Romania7 cities11.2
- 15Hungary8 cities11.0
- 16United States748 cities10.5
- 17Bulgaria6 cities10.3
- 18Lithuania4 cities9.4
- 19Singapore5 cities9.4
- 20Luxembourg3 cities9.1
+ 12 more countries, 8.7 µg/m³ and below
Not counted on this day, too few cities measured: Martinique since 11 Jul 2023, Poland since 29 May 2023 and The Netherlands since 23 May 2023. Days missing from the source archive fall in this window, so fewer countries are counted.
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.