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 30 days to 17 Feb 2024: Pakistan 137.8 µg/m³, India 75.5 µg/m³ and China 49.5 µg/m³.
- 1Pakistan4 cities137.8
- 2India5 cities75.5
- 3China3 cities49.5
- 4North Macedonia7 cities48.9
- 5Thailand72 cities, was 939.7
- 6Serbia12 cities, was 339.2
- 7Montenegro3 cities38.9
- 8Italy22 cities21.6
- 9Romania8 cities20.1
- 10Peru5 cities19.4
- 11Chile45 cities19.0
- 12Hong Kong13 cities19.0
- 13Bulgaria6 cities17.8
- 14Slovakia24 cities16.6
- 15Greece10 cities16.1
- 16Poland77 cities16.0
- 17Hungary9 cities15.5
- 18Czechia37 cities14.2
- 19South Africa9 cities13.6
- 20Spain106 cities12.4
+ 20 more countries, 12.4 µg/m³ and below
- 37United States777 cities6.8
Not counted on this day, too few cities measured: Iceland since 15 Feb 2024, Reunion since 20 Jan 2024 and Malta since 6 Jan 2024. Days missing from the source archive fall in this window, so fewer countries are counted.
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.