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 7 Sep 2023: Pakistan 39.4 µg/m³, Chile 30.2 µg/m³ and India 27.1 µg/m³.
- 1Pakistan4 cities39.4
- 2Chile42 cities30.2
- 3India5 cities27.1
- 4Peru4 cities23.5
- 5China3 cities23.1
- 6Thailand11 cities15.3
- 7Mexico37 cities15.2
- 8Singapore5 cities14.4
- 9Malta4 cities14.0
- 10Greece7 cities13.5
- 11Serbia3 cities13.1
- 12Martinique3 cities12.3
- 13Slovakia27 cities11.7
- 14Hong Kong13 cities11.6
- 15North Macedonia7 cities11.3
- 16Hungary7 cities11.2
- 17Czechia34 cities11.1
- 18Canada115 cities10.4
- 19Romania6 cities10.4
- 20Italy20 cities10.3
+ 15 more countries, 9.7 µg/m³ and below
- 22United States761 cities9.3
Not counted on this day, too few cities measured: Poland since 21 Aug 2023, Reunion since 16 Aug 2023, Lithuania since 27 Jul 2023 and Luxembourg since 27 Jul 2023.
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.