ABSTRACT
Air quality is a global concern due to technological advancements and human activities that have degraded air quality, affecting life quality, lifespan, and ecosystems. The link between air pollution and human health, including mortality and morbidity, is well established. This study was designed to establish baseline levels of Polycyclic Aromatic Hydrocarbons (PAHs) and Polybrominated Diphenyl Ethers (PBDEs) around selected petrol stations in Benin City, Nigeria.This was done to assess not only determine their concentrations but also the potential health risks associated with these known carcinogens. The concentrations of PAHs and PBDEs were determined using a passive sampling method. Polyurethane Foam (PUF) discs were deployed from July 2020 to December 2021 across nineteen sampling locations (twelve urban, six rural, and one control site). Air samples were trapped at a height of 1.5 - 2.0 m. Samples were harvested after 28 days and taken to the laboratory for analysis. The samples were extracted using standard methods and further analyzed, using a Gas Chromatography equipped with a Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS), for PAHs and PBDEs respectively. Sixteen USEPA priority PAHs and penta, octa, and deca congeners of PBDEs were targeted. Results obtained revealed a PBDE concentrations range from 4.590 to 146.420 ng/m³, with the highest concentration obtained at DVD Auchi Road while the lowest concentration was obtained at Iyowa Filling Station. The control site showed a PBDE range of 0.002-0.070 ng/m³. BDE 209 and 205, were found to be the most predominant PBDE obtained. Seasonal variations showed higher ∑PBDE concentrations during the dry season; ranging from ∑25.690 ng/m3 to ∑160.270 ng/m3 compared to the wet season ; ranging from ∑4.590ng/m3 to ∑86.880 ng/m3. PAH concentrations were found to be highest at Mobil Oba Market Road, with concentration ranging from 1164.978 to 1973.883 ng/m³. Benzo(g,h,i)perylene was observed to be the most abundant PAH congener. The sampling locations recorded significantly higher PAH levels than the control site, Seasonal variations showed the dry season samples having higher concentrations likely due to increased combustion activities within these sampling times. Diagnostic ratios like phenanthrene/anthracene and fluoranthene/pyrene revealed pyrolytic origin primarily from fossil fuel combustion as a main source of the PAHs studied which was further confirmed by Principal Component Analysis (PCA). The combined increased lifetime cancer risks due to continuous PAH exposure were assessed, with benzo(a)anthracene significantly contributing to human exposure. The concentrations were compared to regulatory standards from DPR, Canada, and Australia, and were significantly higher than the safe values (p<0.05). Health impact assessments reported neurological and respiratory symptoms linked to PAH and PBDE exposure. These findings underscore the urgent need for mitigation measures to reduce pollution and human exposure to these hazardous pollutants.
