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 21 Feb 2024: Pakistan 110.2 µg/m³, India 73.4 µg/m³ and China 49.7 µg/m³.
- 1Pakistan4 cities110.2
- 2India5 cities73.4
- 3China3 cities49.7
- 4North Macedonia9 cities48.7
- 5Serbia18 cities, was 339.6
- 6Montenegro3 cities39.1
- 7Thailand75 cities, was 938.2
- 8Italy36 cities30.8
- 9Chile45 cities19.1
- 10Romania10 cities19.0
- 11Bulgaria6 cities18.4
- 12Hong Kong13 cities18.4
- 13Peru6 cities17.4
- 14Greece10 cities16.8
- 15Slovakia42 cities15.7
- 16Poland78 cities15.1
- 17South Africa9 cities14.9
- 18Hungary10 cities13.9
- 19Mexico13 cities, was 4412.8
- 20Spain125 cities12.3
+ 21 more countries, 12.1 µg/m³ and below
- 36United States781 cities6.7
Not counted on this day, too few cities measured: 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.