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 25 Sep 2023: Pakistan 38.6 µg/m³, Peru 26.6 µg/m³ and Chile 25.7 µg/m³.
- 1Pakistan4 cities38.6
- 2Peru4 cities26.6
- 3Chile43 cities25.7
- 4India5 cities23.1
- 5China3 cities22.2
- 6Mexico42 cities14.9
- 7Singapore5 cities14.9
- 8Greece7 cities14.2
- 9Thailand11 cities14.1
- 10Serbia3 cities12.8
- 11Malta4 cities12.0
- 12Poland57 cities11.7
- 13Czechia35 cities10.8
- 14Hungary9 cities10.5
- 15Italy30 cities10.2
- 16Hong Kong11 cities9.5
- 17Slovakia27 cities9.4
- 18Bulgaria6 cities9.3
- 19Martinique3 cities9.0
- 20Belgium41 cities8.7
+ 15 more countries, 8.4 µg/m³ and below
- 25United States763 cities7.7
Not counted on this day, too few cities measured: North Macedonia since 20 Sep 2023 and Reunion since 16 Aug 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.