Concentration levels, sources and health risk assessment of atmospheric polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) mainly from the incomplete combustion of organic materials, and are bioaccumulative and toxic(carcinogenic, teratogenic and mutagenic), are a kind of persistent toxic substance. This paper reviews the classification, emission characteristics, temporal and spatial distribution characteristics, source analysis and health risk assessment of atmospheric PAHs, and lists the ways of classifying PAHs according to different molecular weight, existence form and chemical structure. It is pointed out that PAHs concentration presents seasonal variation, and the variation trend is from high to low: winter, spring, autumn and summer. The advantages and disadvantages of molecular diagnostic ratio (DRs) and receptor models, including principal component analysis(PCA), chemical mass balance(CMB), positive matrix factorization (PMF)and Unmix were compared. Source analysis shows that DRs and PCA are the most widely used methods, but the accuracy of source analysis results is affected by many factors. The combination of PMF and Unmix to resolve PAHs sources can assign sources based solely on measured concentrations at the receptor site, providing a time series of PAHs source contributions and making up for the limitations that require human interpretation. This paper shows how the incremental lifetime cancer risk (ILCR)model can be used to assign sources of PAHs to assess health risk, and identify key factors that affect the accuracy of ILCR. We hope this review can provide reference for further research on atmospheric PAHs pollution.