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 25 Sep 2023: Pakistan 46.6 µg/m³, Peru 25.7 µg/m³ and Chile 21.9 µg/m³.
- 1Pakistan3 cities46.6
- 2Peru4 cities25.7
- 3Chile44 cities21.9
- 4Greece7 cities19.6
- 5Thailand11 cities18.7
- 6China3 cities18.5
- 7India4 cities17.2
- 8Mexico42 cities14.7
- 9Malta4 cities13.1
- 10Serbia3 cities12.9
- 11Singapore5 cities11.5
- 12Hong Kong13 cities9.5
- 13Hungary9 cities9.0
- 14Poland48 cities8.8
- 15Czechia35 cities8.5
- 16Romania6 cities8.5
- 17Canada117 cities8.2
- 18Bulgaria5 cities8.1
- 19Italy28 cities7.7
- 20United States766 cities7.6
+ 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.