Bad-air episodes in Japan
5 times since January 2023, many cities in Japan had air at least twice as dirty as their usual for the time of year on the same days. The largest reached 131 cities: Japan, November 2023.
2023
- Japan, December 202329 to 31 December 2023, 3 days20 cities31Tsushima
- Japan, December 20239 to 10 December 2023, 2 days21 cities45Chikusei
- Okayama and Fukuoka, Japan, November 202322 to 23 November 2023, 2 days9 cities29Kasaoka
- Japan, November 20232 to 5 November 2023, 4 days131 cities46Kurashiki
- Japan, October 202319 October 2023, 1 day8 cities35Tsurusaki
Each row: one bar per day, as tall as the number of cities counted that day and coloured by their median level; the number of cities; the highest daily reading and where. An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes.