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 28 Jul 2023: Chile 41.2 µg/m³, Pakistan 27.8 µg/m³ and Malta 22.5 µg/m³.
- 1Chile44 cities41.2
- 2Pakistan4 cities27.8
- 3Malta4 cities22.5
- 4China3 cities19.9
- 5Peru4 cities19.5
- 6Greece8 cities17.2
- 7Mexico39 cities, was 1214.4
- 8Thailand11 cities13.6
- 9Singapore5 cities13.5
- 10North Macedonia7 cities12.1
- 11Hong Kong12 cities11.4
- 12United States742 cities10.5
- 13Canada117 cities10.3
- 14Serbia3 cities10.2
- 15Romania6 cities9.7
- 16India5 cities9.5
- 17Bulgaria6 cities9.0
- 18Slovakia27 cities8.5
- 19Hungary8 cities7.6
- 20Czechia29 cities7.4
+ 13 more countries, 6.9 µg/m³ and below
Not counted on this day, too few cities measured: Italy since 28 Jul 2023, Martinique since 28 Jul 2023, Poland since 26 Jul 2023 and 5 more countries.
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.