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 24 Sep 2023: Pakistan 45.3 µg/m³, Peru 27.1 µg/m³ and Chile 22.3 µg/m³.
- 1Pakistan3 cities45.3
- 2Peru4 cities27.1
- 3Chile44 cities22.3
- 4China3 cities18.4
- 5Thailand10 cities17.9
- 6Greece7 cities17.8
- 7India4 cities17.2
- 8Mexico41 cities14.0
- 9Malta4 cities13.9
- 10Serbia3 cities12.6
- 11Singapore5 cities11.0
- 12Hungary9 cities10.1
- 13Poland47 cities9.8
- 14Hong Kong12 cities9.3
- 15Czechia35 cities9.0
- 16Italy28 cities8.8
- 17Romania6 cities8.3
- 18Canada116 cities7.9
- 19United States766 cities7.8
- 20Bulgaria5 cities7.6
+ 16 more countries, 7.6 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.