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 18 Sep 2023: Pakistan 41.6 µg/m³, Peru 28.6 µg/m³ and China 25.3 µg/m³.
- 1Pakistan4 cities41.6
- 2Peru4 cities28.6
- 3China3 cities25.3
- 4Chile43 cities23.0
- 5India5 cities18.3
- 6Mexico42 cities15.2
- 7Singapore5 cities14.5
- 8Serbia3 cities13.9
- 9Czechia36 cities13.5
- 10Poland62 cities13.5
- 11Hungary9 cities13.2
- 12Malta4 cities13.1
- 13Italy30 cities12.9
- 14Greece7 cities12.5
- 15Thailand9 cities12.1
- 16Slovakia27 cities12.0
- 17Bulgaria6 cities11.7
- 18Austria30 cities10.0
- 19Belgium41 cities9.5
- 20Romania6 cities9.4
+ 16 more countries, 9.0 µg/m³ and below
- 28United States755 cities6.7
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.