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 22 Sep 2024: Pakistan 74.6 µg/m³, India 30.7 µg/m³ and Chile 24.8 µg/m³.
- 1Pakistan3 cities74.6
- 2India5 cities30.7
- 3Chile45 cities24.8
- 4Peru16 cities23.5
- 5Poland73 cities22.6
- 6Singapore6 cities16.9
- 7China3 cities16.6
- 8Thailand18 cities, was 6615.8
- 9Brazil40 cities15.5
- 10Serbia24 cities14.8
- 11Hungary4 cities14.5
- 12The Netherlands22 cities13.5
- 13United Kingdom62 cities12.0
- 14Hong Kong13 cities9.1
- 15Taiwan43 cities7.7
- 16Japan517 cities6.4
- 17United States818 cities6.2
- 18New Zealand5 cities6.1
- 19Bulgaria5 cities5.8
- 20Canada118 cities5.8
+ 4 more countries, the next at 5.7 µg/m³
Not counted on this day, too few cities measured: Mexico since 19 Sep 2024, Belgium since 17 Aug 2024, Switzerland since 17 Aug 2024 and 22 more countries.
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, Turkey and Iran, which publish only on their own websites. We are building the reader for China's network. The networks of Turkey and Iran don't answer requests from outside their countries, so we can't read them. Most cities there are missing from this board, not clean. Why.