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 30 Jul 2023: Chile 41.5 µg/m³, Pakistan 33.3 µg/m³ and China 22.0 µg/m³.
- 1Chile45 cities41.5
- 2Pakistan4 cities33.3
- 3China3 cities22.0
- 4Malta4 cities17.5
- 5Brazil35 cities14.5
- 6Greece8 cities14.5
- 7Mexico12 cities13.7
- 8Thailand11 cities13.4
- 9India5 cities12.3
- 10Serbia3 cities11.9
- 11Romania7 cities11.0
- 12North Macedonia7 cities10.9
- 13Slovakia27 cities10.9
- 14Canada101 cities10.8
- 15United States748 cities10.7
- 16Singapore6 cities10.5
- 17Czechia32 cities10.2
- 18Bulgaria6 cities9.8
- 19Hungary8 cities9.7
- 20Australia25 cities8.7
+ 12 more countries, the next at 7.8 µg/m³
Not counted on this day, too few cities measured: Italy since 29 Jul 2023, Lithuania since 27 Jul 2023, Luxembourg since 27 Jul 2023 and Martinique since 11 Jul 2023. Days missing from the source archive fall in this window, so fewer countries are counted.
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.