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 2024: Chile 36.8 µg/m³, Peru 22.5 µg/m³ and Pakistan 22.0 µg/m³.
- 1Chile41 cities36.8
- 2Peru16 cities22.5
- 3Pakistan3 cities22.0
- 4China4 cities17.5
- 5India4 cities16.1
- 6Singapore5 cities14.1
- 7New Zealand5 cities12.9
- 8Serbia10 cities12.8
- 9Thailand17 cities, was 912.5
- 10Hungary5 cities11.1
- 11Canada115 cities10.5
- 12South Korea141 cities10.4
- 13Poland69 cities9.7
- 14Japan559 cities8.8
- 15Hong Kong11 cities8.7
- 16United States800 cities8.4
- 17Taiwan43 cities7.0
- 18The Netherlands20 cities6.6
- 19Mexico3 cities6.4
- 20Bulgaria5 cities5.7
+ 4 more countries, 5.5 µg/m³ and below
Not counted on this day, too few cities measured: Belgium since 17 Aug 2024, Switzerland since 17 Aug 2024, Germany since 17 Aug 2024 and 22 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.