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 23 Aug 2023: Pakistan 47.9 µg/m³, China 25.9 µg/m³ and India 25.3 µg/m³.
- 1Pakistan4 cities47.9
- 2China3 cities25.9
- 3India5 cities25.3
- 4Chile44 cities22.3
- 5Malta4 cities18.2
- 6Serbia3 cities17.0
- 7Slovakia27 cities15.8
- 8Thailand11 cities15.4
- 9Greece7 cities15.3
- 10Czechia35 cities15.1
- 11Italy21 cities14.7
- 12Hungary7 cities14.2
- 13North Macedonia7 cities13.5
- 14Romania7 cities13.4
- 15Canada117 cities12.3
- 16Mexico13 cities12.3
- 17Singapore5 cities12.2
- 18Switzerland8 cities11.7
- 19Bulgaria6 cities11.2
- 20United States757 cities11.1
+ 11 more countries, 11.0 µg/m³ and below
Not counted on this day, too few cities measured: Martinique since 22 Aug 2023, Australia since 21 Aug 2023, Hong Kong since 21 Aug 2023 and 5 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.