Sources, environmental levels, and health risks of PM2.5-bound polycyclic aromatic hydrocarbons in energy-producing cities in northern China

We collected 170 samples of airborne fine particulate matter from five coal-producing cities and one oil-producing city in northern China during both heating and non-heating periods to quantify the concentrations of 12 polycyclic aromatic hydrocarbons, estimate their bioaccessible fraction, and calculate the incremental lifetime cancer risk (ILCR) of this fraction. The major sources of the particulate matter were analyzed using the chemical mass balance model. We found that the main emission sources were coal combustion during the heating period and open sources during the non-heating period. The ILCR was initially calculated as 2.65 × 10−9 for coal-producing cities and 4.60 × 10−9 for the oil-producing city during the heating period and 1.17 × 10−8 and 3.34 × 10−8, respectively, during the non-heating period. When only the bioaccessible fraction was used, the ILCR in coal-producing cities and the oil-producing city decreased by 87.2% and 82.1%, respectively, for the heating period and by 89.0% and 80.1%, respectively, for the non-heating period. The findings suggest that bioaccessibility should be considered when assessing the carcinogenic risk of polycyclic aromatic hydrocarbons. This study provides insights into the contribution of major emission sources to air pollution related to the long-term exploitation, transportation, and use of coal and oil.