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 30 Jul 2023: Chile 42.9 µg/m³, Pakistan 26.9 µg/m³ and China 21.5 µg/m³.
- 1Chile44 cities42.9
- 2Pakistan4 cities26.9
- 3China3 cities21.5
- 4Malta4 cities18.9
- 5Peru4 cities18.7
- 6Mexico41 cities, was 1214.3
- 7Brazil32 cities14.1
- 8Singapore6 cities13.9
- 9Greece8 cities13.8
- 10Hong Kong12 cities12.8
- 11Thailand11 cities11.6
- 12Serbia3 cities11.1
- 13India5 cities10.7
- 14Romania7 cities10.6
- 15United States742 cities10.2
- 16North Macedonia7 cities9.6
- 17Canada115 cities8.4
- 18Bulgaria6 cities8.3
- 19Slovakia27 cities8.0
- 20Hungary8 cities7.5
+ 14 more countries, the next at 7.1 µg/m³
Not counted on this day, too few cities measured: Italy since 28 Jul 2023, Martinique since 28 Jul 2023, Poland since 26 Jul 2023 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, 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.