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 20 Apr 2024: Laos 64.0 µg/m³, India 44.5 µg/m³ and China 42.6 µg/m³.
- 1Laos3 cities64.0
- 2India5 cities44.5
- 3China4 cities42.6
- 4Pakistan4 cities38.9
- 5Thailand82 cities31.6
- 6Chile44 cities23.0
- 7South Korea138 cities21.2
- 8Malta4 cities19.9
- 9Taiwan43 cities19.9
- 10Peru6 cities18.3
- 11Hong Kong4 cities, was 1317.0
- 12Mexico11 cities16.8
- 13Serbia24 cities15.5
- 14Greece4 cities13.7
- 15North Macedonia7 cities13.7
- 16Poland78 cities13.2
- 17Bosnia and Herzegovina5 cities12.5
- 18Japan513 cities11.4
- 19Czechia37 cities11.2
- 20Latvia4 cities11.2
+ 25 more countries, 11.1 µg/m³ and below
- 37United States787 cities5.6
Not counted on this day, too few cities measured: Montenegro since 26 Mar 2024, Belgium since 20 Mar 2024, Switzerland since 20 Mar 2024 and 3 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 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.