Inhalation exposure to polycyclic aromatic hydrocarbons (PAHs) bound to very fine particles (VFPs): A multi-provincial field investigation in China

Inhalation exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with adverse health effects on populations, with elevated exposure risks observed among users of solid fuels. Very fine particles (VFPs) have the capacity to penetrate deeply into lung, yet there have been few studies examing exposure to VFPs and the surface-bound organic compounds. Herein, PAHs bound to particles with aerodynamic diameters less than 0.25 μm (PM0.25) in inhaled air of rural residents were measured based on a multi-provincial field study. The daily average total concentration of 28 PAH species bound to PM0.25 (PM0.25-PAH28) exposure was 132 ± 244 ng/m3 with distinct spatial difference. Fuel type, cooking practice, and season significantly influenced PAH28 exposure, highlighting the potential health benefits of clean energy transition. The calculated Incremental Lifetime Cancer Risk (ILCR) averaged 9.5×10-5, with an increase to 4.7×10-4 for northern residents in winter, underscoring the non-negligible health risk of rural residents due to inhalation exposure to PM0.25-PAH28. While household solid fuel was the primary source of inhalable PAHs, contributions from neighboring sources and urban air pollution through airflow transport were also observed. This study illuminates the exposure to PAHs bound to PM0.25 across diverse rural settings, highlighting the importance of transitioning to clean household fuels and implementing measures to control urban air pollution.