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 18 Aug 2023: Pakistan 37.9 µg/m³, Chile 31.0 µg/m³ and India 30.6 µg/m³.
- 1Pakistan4 cities37.9
- 2Chile43 cities31.0
- 3India5 cities30.6
- 4China3 cities23.8
- 5Peru4 cities20.0
- 6Martinique3 cities18.9
- 7Thailand11 cities16.3
- 8Malta4 cities15.8
- 9Mexico40 cities, was 1214.9
- 10Serbia3 cities14.8
- 11Singapore5 cities14.6
- 12Slovakia27 cities14.2
- 13Czechia36 cities13.3
- 14Greece7 cities12.5
- 15Poland68 cities12.2
- 16Hungary7 cities11.8
- 17Italy23 cities, was 2611.8
- 18Romania7 cities11.4
- 19North Macedonia7 cities11.3
- 20Hong Kong13 cities10.8
+ 16 more countries, 9.7 µg/m³ and below
- 30United States756 cities7.4
Not counted on this day, too few cities measured: Luxembourg since 17 Aug 2023, Reunion since 9 Aug 2023, Lithuania since 16 Jul 2023 and The Netherlands since 24 Jun 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.