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 23 Aug 2024: Chile 39.9 µg/m³, Pakistan 32.0 µg/m³ and China 22.0 µg/m³.
- 1Chile44 cities39.9
- 2Pakistan4 cities32.0
- 3China4 cities22.0
- 4Brazil33 cities20.6
- 5Peru16 cities20.4
- 6India5 cities17.4
- 7New Zealand5 cities14.6
- 8Malta5 cities14.5
- 9Singapore6 cities13.3
- 10North Macedonia9 cities13.0
- 11Thailand17 cities12.9
- 12Italy7 cities12.8
- 13Slovakia27 cities10.5
- 14Hong Kong13 cities10.2
- 15South Korea140 cities10.1
- 16Serbia12 cities9.6
- 17Hungary7 cities9.3
- 18Poland72 cities9.0
- 19Japan555 cities8.9
- 20Mexico3 cities8.7
+ 17 more countries, the next at 8.7 µg/m³
- 21United States803 cities8.7
Not counted on this day, too few cities measured: Latvia since 23 Aug 2024, Romania since 23 Aug 2024, Martinique since 22 Aug 2024 and 9 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.