Much like the dust‐borne particles that spike in April (the so‐called “yellow dust” season), black carbon can also rise that time of year because the same seasonal winds that carry Gobi‐desert dust into Korea can also transport combustion‐related pollutants (including black carbon) from upwind source regions in China and beyond.
In addition, early spring is often dry and sometimes involves biomass burning (e.g. agricultural field burning), which can release extra black carbon into the atmosphere. All of this converges in April, making black carbon levels climb alongside the well‐known dust peaks.