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 31 Mar 2023: China 40.5 µg/m³, Pakistan 33.2 µg/m³ and Thailand 25.7 µg/m³.
- 1China4 cities40.5
- 2Pakistan4 cities33.2
- 3Thailand77 cities25.7
- 4Chile43 cities24.9
- 5Mexico50 cities24.8
- 6Peru5 cities15.6
- 7South Africa11 cities13.8
- 8Brazil13 cities13.5
- 9Hong Kong11 cities12.6
- 10Greece8 cities12.4
- 11Poland63 cities11.5
- 12Romania7 cities10.8
- 13Singapore5 cities9.6
- 14Slovakia25 cities9.6
- 15Bulgaria7 cities9.5
- 16Czechia22 cities9.0
- 17Italy20 cities8.7
- 18Spain86 cities8.4
- 19Ireland4 cities8.0
- 20Hungary7 cities7.9
+ 14 more countries, 6.8 µg/m³ and below
- 21United States686 cities6.8
Not counted on this day, too few cities measured: Sweden since 29 Mar 2023, Kosovo since 28 Mar 2023, Luxembourg since 26 Mar 2023 and 8 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 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.