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 30 Sep 2023: Pakistan 42.8 µg/m³, Peru 26.6 µg/m³ and Chile 24.2 µg/m³.
- 1Pakistan4 cities42.8
- 2Peru4 cities26.6
- 3Chile43 cities24.2
- 4China3 cities23.6
- 5India5 cities22.8
- 6Singapore5 cities16.2
- 7Mexico42 cities14.9
- 8Thailand10 cities14.5
- 9Greece7 cities14.2
- 10Malta4 cities13.9
- 11Serbia3 cities13.2
- 12Poland53 cities12.7
- 13Czechia36 cities12.1
- 14Italy31 cities, was 411.2
- 15Hungary9 cities11.0
- 16Slovakia27 cities9.9
- 17Hong Kong11 cities9.6
- 18Bulgaria6 cities9.5
- 19Romania6 cities9.3
- 20Belgium41 cities8.9
+ 15 more countries, 8.7 µg/m³ and below
- 26United States770 cities7.7
Not counted on this day, too few cities measured: North Macedonia since 20 Sep 2023 and Reunion since 16 Aug 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.