Linfen is in the mid-Eastern PRC
It has a humid environment, and is in a valley so temperature inversions occur frequently, trapping in smog. This is worst in winter, where more fuel is used for heating buildings. Less rain and wind occurs to remove smog from the area.
Factories in Linfen producing green technology still primarily rely on coal to fuel them.
In the PRC, there is a new coal powered energy plant each week.