(a) PM2.5 concentration averaged in 2013–20. The rectangular box indicates the NCP region. (b) Annual mean PM2.5 concentration and the contribution from ND over the NCP. The original data have been detrended. (c) Atmospheric extinction coefficient (1980–2013) derived from visibility and PM2.5 concentration data (2013–20) in September to December ...
View more: Haze pollution levels exhibit short-term seesaw behavior over North China Plain