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 4 Dec 2023: Pakistan 105.6 µg/m³, India 101.8 µg/m³ and China 33.4 µg/m³.
- 1Pakistan3 cities105.6
- 2India4 cities101.8
- 3China3 cities33.4
- 4Thailand9 cities25.5
- 5North Macedonia7 cities24.0
- 6Hong Kong13 cities18.9
- 7Chile37 cities18.0
- 8Serbia3 cities17.7
- 9Mexico41 cities, was 1116.9
- 10Romania7 cities13.5
- 11Bulgaria6 cities13.0
- 12Greece8 cities12.5
- 13Czechia31 cities12.1
- 14Slovakia27 cities11.8
- 15Hungary8 cities11.7
- 16Italy21 cities11.6
- 17Lithuania4 cities10.9
- 18Martinique3 cities9.9
- 19Singapore5 cities9.7
- 20Austria29 cities8.9
+ 14 more countries, 8.7 µg/m³ and below
- 24United States769 cities7.8
Not counted on this day, too few cities measured: Malta since 11 Nov 2023, Ireland since 6 Nov 2023, Peru since 21 Oct 2023 and Poland since 8 Oct 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.