Here we present a quantitative source apportionment of WSOC, isolated from aerosols in China using radiocarbon (¹⁴C) and offline high-resolution time of flight aerosol mass spectrometer measurements. We demonstrate a dominant contribution of non-fossil emissions to WSOC aerosols in the Northern Hemisphere. However, the fossil fraction is substantially larger in aerosols from East Asia and the east Asian pollution outflow, especially during winter, due to increasing coal combustion.