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 19 Sep 2023: Pakistan 38.7 µg/m³, Peru 28.1 µg/m³ and China 25.5 µg/m³.
- 1Pakistan4 cities38.7
- 2Peru4 cities28.1
- 3China3 cities25.5
- 4Chile44 cities24.0
- 5India5 cities17.7
- 6Mexico43 cities15.2
- 7Serbia3 cities13.8
- 8Singapore5 cities13.4
- 9Thailand10 cities13.2
- 10Greece7 cities12.8
- 11Malta4 cities12.6
- 12Italy30 cities12.1
- 13Bulgaria6 cities12.0
- 14Czechia36 cities11.9
- 15Hungary9 cities11.8
- 16Poland58 cities11.7
- 17Slovakia27 cities10.3
- 18Romania6 cities9.3
- 19Japan546 cities8.3
- 20Austria30 cities8.2
+ 16 more countries, 8.0 µg/m³ and below
- 25United States757 cities6.9
Not counted on this day, too few cities measured: North Macedonia since 16 Sep 2023, Lithuania since 11 Sep 2023 and Luxembourg since 6 Sep 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.