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 27 Sep 2023: Pakistan 52.2 µg/m³, China 28.6 µg/m³ and Peru 24.4 µg/m³.
- 1Pakistan3 cities52.2
- 2China3 cities28.6
- 3Peru5 cities24.4
- 4India4 cities21.3
- 5Chile44 cities20.5
- 6Greece7 cities20.4
- 7Thailand10 cities17.9
- 8Mexico42 cities15.4
- 9Singapore5 cities14.8
- 10Serbia3 cities13.7
- 11Malta4 cities12.6
- 12Poland61 cities10.6
- 13Czechia35 cities10.3
- 14Hungary10 cities10.2
- 15Hong Kong13 cities10.0
- 16Romania6 cities10.0
- 17Canada117 cities9.2
- 18Italy27 cities8.5
- 19Slovakia27 cities8.5
- 20Bulgaria5 cities8.2
+ 15 more countries, 7.2 µg/m³ and below
- 21United States767 cities7.2
Not counted on this day, too few cities measured: Reunion since 26 Sep 2023, 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.