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 28 Oct 2023: Pakistan 88.1 µg/m³, India 70.4 µg/m³ and China 57.6 µg/m³.
- 1Pakistan3 cities88.1
- 2India4 cities70.4
- 3China3 cities57.6
- 4Thailand9 cities22.4
- 5Chile15 cities20.0
- 6Greece9 cities17.8
- 7North Macedonia7 cities15.0
- 8Singapore6 cities14.4
- 9Malta4 cities13.4
- 10Mexico11 cities, was 4212.8
- 11Brazil30 cities12.3
- 12Romania6 cities10.4
- 13Serbia3 cities9.4
- 14Japan528 cities9.3
- 15Hungary6 cities8.3
- 16Czechia34 cities8.2
- 17Bulgaria6 cities7.7
- 18Italy21 cities7.2
- 19United States747 cities6.9
- 20Canada118 cities6.6
+ 16 more countries, the next at 6.5 µg/m³
Not counted on this day, too few cities measured: Hong Kong since 17 Oct 2023, Peru since 17 Oct 2023, Poland since 1 Oct 2023 and Luxembourg since 6 Sep 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.