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 1 Aug 2023: Chile 40.2 µg/m³, Pakistan 33.3 µg/m³ and China 21.4 µg/m³.
- 1Chile44 cities40.2
- 2Pakistan4 cities33.3
- 3China3 cities21.4
- 4Malta4 cities17.4
- 5Greece8 cities14.2
- 6Martinique3 cities14.1
- 7Thailand11 cities13.7
- 8India5 cities13.1
- 9Mexico13 cities13.1
- 10Serbia3 cities11.6
- 11North Macedonia7 cities11.0
- 12Romania7 cities10.8
- 13Singapore5 cities10.8
- 14Slovakia27 cities10.4
- 15Canada106 cities10.2
- 16United States750 cities10.2
- 17Bulgaria6 cities9.7
- 18Czechia26 cities9.7
- 19Hungary8 cities9.4
- 20Spain83 cities7.9
+ 11 more countries, 6.8 µg/m³ and below
Not counted on this day, too few cities measured: Italy since 29 Jul 2023, Lithuania since 27 Jul 2023 and Luxembourg since 27 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 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.