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 27 Jul 2023: Chile 35.6 µg/m³, Pakistan 30.2 µg/m³ and China 25.3 µg/m³.
- 1Chile44 cities35.6
- 2Pakistan4 cities30.2
- 3China3 cities25.3
- 4Malta4 cities25.0
- 5Peru4 cities20.3
- 6Greece8 cities18.2
- 7Mexico39 cities, was 1214.9
- 8Thailand11 cities14.6
- 9Martinique3 cities14.4
- 10Italy23 cities, was 2613.2
- 11Singapore5 cities13.2
- 12North Macedonia7 cities12.9
- 13Serbia3 cities10.8
- 14United States743 cities10.4
- 15Hong Kong12 cities10.2
- 16Romania6 cities10.2
- 17Canada120 cities10.1
- 18Bulgaria6 cities9.6
- 19India5 cities9.1
- 20Slovakia27 cities8.9
+ 15 more countries, 8.1 µg/m³ and below
Not counted on this day, too few cities measured: Poland since 26 Jul 2023, Lithuania since 16 Jul 2023, Luxembourg since 16 Jul 2023 and 3 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.