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 28 Dec 2024: Pakistan 263.7 µg/m³, India 123.9 µg/m³ and Thailand 38.0 µg/m³.
- 1Pakistan3 cities263.7
- 2India4 cities123.9
- 3Thailand16 cities38.0
- 4Hong Kong13 cities36.0
- 5China4 cities35.3
- 6Serbia19 cities32.5
- 7Poland72 cities26.5
- 8Mexico15 cities23.2
- 9Martinique3 cities22.3
- 10Czechia39 cities20.3
- 11Slovenia12 cities20.0
- 12Slovakia42 cities19.7
- 13Hungary11 cities18.3
- 14Chile45 cities17.9
- 15Peru17 cities16.9
- 16Croatia5 cities16.7
- 17South Korea141 cities15.8
- 18Bulgaria8 cities15.1
- 19Taiwan42 cities13.1
- 20Romania10 cities12.7
+ 25 more countries, 12.6 µg/m³ and below
- 31United States825 cities8.4
Not counted on this day, too few cities measured: Lithuania since 28 Dec 2024, Bosnia and Herzegovina since 27 Dec 2024, Puerto Rico since 7 Dec 2024 and Kosovo since 24 Nov 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.