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 15 Jan 2025: Pakistan 187.5 µg/m³, India 96.1 µg/m³ and China 41.9 µg/m³.
- 1Pakistan3 cities187.5
- 2India5 cities96.1
- 3China4 cities41.9
- 4Serbia19 cities40.3
- 5Thailand16 cities39.5
- 6Hong Kong13 cities32.4
- 7Bulgaria8 cities26.6
- 8Slovenia12 cities22.8
- 9Romania10 cities22.2
- 10Hungary11 cities20.1
- 11Mexico14 cities19.3
- 12Greece8 cities18.9
- 13Czechia35 cities18.8
- 14Poland67 cities18.6
- 15Slovakia42 cities18.5
- 16South Korea141 cities18.1
- 17Chile45 cities17.6
- 18Peru17 cities16.3
- 19Taiwan43 cities15.5
- 20Austria36 cities13.8
+ 23 more countries, 11.3 µg/m³ and below
- 34United States834 cities7.1
Not counted on this day, too few cities measured: Croatia since 15 Jan 2025, Bosnia and Herzegovina since 12 Jan 2025, Martinique since 9 Jan 2025 and Lithuania since 1 Jan 2025.
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.