Quantitative source apportionment and health risk assessment for polycyclic aromatic hydrocarbon and their derivatives in indoor dust from housing and public buildings of a mega-city in China

Indoor dust can adsorb various pollutants and long-term deposition can significantly impact air quality and human health. This study investigated the occurrence, source apportionment, and health risks associated with polycyclic aromatic hydrocarbons (PAHs) and their derivatives (d-PAHs) in indoor dust, by focusing on residential and public buildings in Nanjing, China. The concentration of 16 PAHs and 27 d-PAHs ranged from 511 to 5472 ng/g and from 422 to 2904 ng/g, with the most abundant compounds being fluoranthene and 1,2-benz[a]anthraquinone, respectively. The total concentrations observed in residences and station halls were higher than in student dormitory and offices. The primary source of PAHs and d-PAHs was identified as coal combustion by self-organizing map combined with receptor models, including principal component analysis-multiple linear regression (PCA-MLR) and positive matrix factorization (PMF). Compared with PCA-MLR, PMF demonstrated superior performance and was recommended as the preferred model for quantitative source analysis. PAHs and d-PAHs in indoor dust may pose a high incremental lifetime carcinogenic risk (˃ 1 × 10^-4) through inhalation and dermal exposure based on Monte Carlo simulation. PAH derivatives posed a risk of 70 % of the total target compounds, although their concentration only accounted for 30 %. Notably, children exhibited a higher risk through ingestion than adults, which can be attributed to hand-to-mouth and object-to-mouth contact behaviors. This work helps to understand PAHs and d-PAHs in urban indoor dust from both outdoor environments and indoor activities, offering an innovative perspective for tracing indoor environmental pollution sources and risks.