Distribution and source apportionment of polycyclic aromatic hydrocarbons in indoor dust of an emerging residential city in Nigeria: Implication on human health

Abstract

In this study, the concentrations and sources of 16 selected polycyclic aromatic hydrocarbons (PAHs) in residential dust of Osogbo metropolis, Nigeria were determined and associated health risks were evaluated. Residential dust samples were collected from different regions and sub-regions of the Osogbo local government, subjected to extraction using suitable solvents and analyzed using a Gas Chromatography-Mass spectrometer. Concentrations of detected Σ16PAHs ranged from 0.023–26.03 μg/kg. High-molecular-weight PAHs (four to six rings) were the predominant contributors to the PAH burden in the street dust, accounting for 68 % of the total PAHs. Also, chrysene and its alkylated derivative (3-methylchrysene) were the most abundant of the quantified PAHs in the dust samples accounting for 28 % and 19 % respectively. Evaluation of increment lifetime cancer risk indicated that ingestion and dermal contact (10 −4 and 10 −5 ) were found to be an exposure pathway leading to carcinogenic risk. The result also indicates that children are more vulnerable to daily exposure after a long time, particularly through ingestion. The result of the PAH diagnostic ratio suggested mixed emissions from the combustion of biomass and fossil fuels. However, the source-oriented PMF model suggested petroleum combustion, tobacco smoke emission, biomass and wood combustion, and cooking gas emissions which account for 15 %, 22 %, 38 % and 25 % respectively. The findings highlight the necessity of focused actions to reduce exposure to PAHs and safeguard susceptible groups. Effective methods to enhance indoor air quality and lower the related health risks can be informed by knowledge of the various sources of PAH emissions. • The study determined the distribution of PAHs in residential dusts. • Concentrations of detected Σ16PAHs ranged from 0.023–26.03 μg/kg. • High-molecular-weight PAHs dominate, making up 68 % of total PAHs. • Children are at higher risk from long-term PAH exposure, especially via ingestion. • PAH sources include biomass, fossil fuel combustion, and tobacco smoke.