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 5 Sep 2023: Pakistan 37.2 µg/m³, India 36.0 µg/m³ and Chile 28.6 µg/m³.
- 1Pakistan4 cities37.2
- 2India5 cities36.0
- 3Chile42 cities28.6
- 4China3 cities26.7
- 5Peru4 cities23.4
- 6Singapore5 cities19.4
- 7Mexico46 cities16.8
- 8Martinique3 cities14.2
- 9Thailand10 cities14.2
- 10Hong Kong13 cities12.8
- 11Serbia3 cities11.5
- 12Greece8 cities10.7
- 13United Kingdom5 cities10.6
- 14Bulgaria6 cities9.0
- 15North Macedonia7 cities9.0
- 16Malta4 cities9.0
- 17Poland67 cities8.6
- 18Italy27 cities8.5
- 19Canada117 cities8.1
- 20Belgium41 cities7.9
+ 18 more countries, 7.8 µg/m³ and below
- 22United States756 cities7.7
Not counted on this day, too few cities measured: Reunion since 9 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.