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 20 Sep 2023: Pakistan 37.8 µg/m³, Peru 26.4 µg/m³ and China 24.5 µg/m³.
- 1Pakistan4 cities37.8
- 2Peru4 cities26.4
- 3China3 cities24.5
- 4Chile44 cities23.5
- 5India5 cities17.8
- 6Mexico42 cities15.0
- 7Thailand10 cities14.2
- 8Greece7 cities13.4
- 9Malta4 cities13.2
- 10Serbia3 cities12.7
- 11Singapore5 cities12.6
- 12Bulgaria6 cities12.0
- 13Italy30 cities11.7
- 14Hungary9 cities9.9
- 15Poland57 cities9.9
- 16Czechia35 cities9.5
- 17Romania6 cities9.4
- 18Japan554 cities9.0
- 19Slovakia27 cities8.4
- 20United States761 cities7.4
+ 16 more countries, 7.3 µg/m³ and below
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.