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 19 Apr 2024: Laos 62.7 µg/m³, India 44.0 µg/m³ and China 41.5 µg/m³.
- 1Laos3 cities62.7
- 2India5 cities44.0
- 3China4 cities41.5
- 4Pakistan4 cities39.8
- 5Thailand80 cities31.3
- 6Chile44 cities22.8
- 7South Korea136 cities21.1
- 8Taiwan43 cities20.0
- 9Malta3 cities19.9
- 10Peru4 cities18.1
- 11Mexico11 cities16.5
- 12Serbia24 cities15.3
- 13Greece4 cities14.0
- 14Poland77 cities14.0
- 15North Macedonia6 cities13.5
- 16Bosnia and Herzegovina5 cities12.5
- 17Czechia35 cities11.5
- 18Latvia4 cities11.3
- 19Romania5 cities, was 1011.2
- 20Japan509 cities11.1
+ 24 more countries, 11.1 µg/m³ and below
- 37United States788 cities5.5
Not counted on this day, too few cities measured: Hong Kong since 26 Mar 2024, Montenegro since 26 Mar 2024, Belgium since 20 Mar 2024 and 4 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.