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 28 Dec 2024: Pakistan 168.5 µg/m³, India 117.2 µg/m³ and Serbia 37.5 µg/m³.
- 1Pakistan3 cities168.5
- 2India4 cities117.2
- 3Serbia25 cities37.5
- 4China4 cities35.5
- 5Thailand16 cities32.5
- 6Hong Kong13 cities28.0
- 7Slovenia12 cities22.5
- 8Poland70 cities20.8
- 9Croatia5 cities19.0
- 10Hungary11 cities18.8
- 11Bulgaria8 cities18.5
- 12Peru18 cities18.4
- 13Mexico12 cities18.2
- 14Chile46 cities18.0
- 15Romania9 cities15.7
- 16Greece7 cities15.4
- 17South Korea141 cities15.3
- 18Slovakia39 cities14.7
- 19Taiwan43 cities14.0
- 20Czechia37 cities13.7
+ 23 more countries, 11.1 µg/m³ and below
- 33United States823 cities7.6
Not counted on this day, too few cities measured: Bosnia and Herzegovina since 28 Dec 2024, France since 19 Dec 2024, Martinique since 18 Dec 2024 and Luxembourg since 7 Dec 2024.
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.