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 28 Oct 2023: India 61.5 µg/m³, Pakistan 58.7 µg/m³ and China 33.0 µg/m³.
- 1India4 cities61.5
- 2Pakistan4 cities58.7
- 3China3 cities33.0
- 4Chile45 cities21.6
- 5Singapore6 cities20.6
- 6Thailand10 cities20.1
- 7Malta4 cities16.4
- 8Serbia3 cities16.3
- 9Greece8 cities14.6
- 10North Macedonia7 cities13.8
- 11Italy29 cities, was 412.6
- 12Brazil26 cities11.5
- 13Czechia35 cities11.3
- 14Hungary6 cities11.3
- 15Mexico11 cities, was 3711.0
- 16Romania7 cities10.6
- 17Slovakia27 cities10.3
- 18Bulgaria6 cities9.5
- 19Austria30 cities9.0
- 20Switzerland8 cities8.7
+ 14 more countries, the next at 8.4 µg/m³
- 30United States768 cities6.6
Not counted on this day, too few cities measured: Hong Kong since 22 Oct 2023, Peru since 21 Oct 2023 and Poland since 8 Oct 2023.
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.