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 4 Dec 2023: India 91.6 µg/m³, Thailand 30.8 µg/m³ and China 30.7 µg/m³.
- 1India4 cities91.6
- 2Thailand9 cities30.8
- 3China3 cities30.7
- 4Hong Kong13 cities26.4
- 5North Macedonia7 cities26.3
- 6Romania7 cities22.9
- 7Italy6 cities, was 2822.4
- 8Czechia35 cities19.5
- 9Serbia3 cities18.8
- 10Lithuania3 cities18.6
- 11Bulgaria5 cities17.6
- 12Chile38 cities17.0
- 13Slovakia27 cities16.8
- 14Austria28 cities16.5
- 15Greece9 cities16.2
- 16Mexico47 cities, was 1116.1
- 17Ireland3 cities15.5
- 18Belgium41 cities15.1
- 19Hungary6 cities14.5
- 20Germany205 cities12.3
+ 16 more countries, 12.3 µg/m³ and below
- 25United States737 cities8.0
Not counted on this day, too few cities measured: Martinique since 1 Dec 2023, Pakistan since 1 Dec 2023 and Peru since 17 Oct 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.