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 15 Apr 2024: Laos 53.1 µg/m³, China 46.6 µg/m³ and Thailand 38.9 µg/m³.
- 1Laos3 cities53.1
- 2China4 cities46.6
- 3Thailand76 cities38.9
- 4India5 cities34.9
- 5Pakistan4 cities33.7
- 6Peru5 cities27.3
- 7Chile46 cities23.7
- 8Taiwan42 cities22.9
- 9Mexico11 cities19.1
- 10Hong Kong8 cities18.0
- 11South Korea140 cities17.4
- 12Malta4 cities15.5
- 13Serbia24 cities15.1
- 14North Macedonia9 cities13.6
- 15Greece4 cities13.0
- 16Romania6 cities12.4
- 17Slovakia39 cities12.0
- 18Italy35 cities, was 3911.9
- 19Poland77 cities11.4
- 20Slovenia12 cities10.8
+ 25 more countries, 10.6 µg/m³ and below
- 35United States784 cities5.7
Not counted on this day, too few cities measured: Kosovo since 15 Apr 2024, Belgium since 13 Apr 2024, Montenegro since 22 Mar 2024 and 5 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.