Environmental Occurrence of PAHs, Their FTIR-Derived Functional Groups, and Human Health Risks of Deposited Dust from Hospitals in Northwestern Nigeria

Background The study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs), associated functional groups, and potential human health risks in deposited dust from selected teaching hospitals in Northwestern Nigeria. Methods Deposited dust samples were collected from indoor, outdoor, and junction areas of five teaching hospitals and analyzed for 16 PAHs using gas chromatography–flame ionization detection (GC-FID). Fourier Transform Infrared (FTIR) spectroscopy was used to identify functional groups in the dust matrix. Hierarchical cluster analysis of PAH concentrations was conducted in Minitab 22 to assess spatial similarities among sampling environments. Human health risks were evaluated using the U.S. EPA model by estimating chronic daily intake for adults and children via ingestion, inhalation, and dermal contact. Non-carcinogenic risk was expressed as the Hazard Index, while carcinogenic risk was assessed using incremental lifetime cancer risk based on benzo(a)pyrene equivalency and interpreted against the U.S. EPA acceptable range (10⁻⁶–10⁻⁴). Results Total PAH concentrations (Σ16PAHs) were detected in all deposited dust samples. Molecular weight distribution indicated dominance of high-molecular-weight PAHs (4–6 rings), including benzo(a)pyrene, benzo(b)fluoranthene, chrysene, and indeno(1,2,3-cd)pyrene. FTIR spectra consistently showed absorption bands at 3420 cm⁻¹ (O–H), 3050 cm⁻¹ (aromatic C–H), 2920–2850 cm⁻¹ (aliphatic C–H), 1705 cm⁻¹ (C = O), and 1600 cm⁻¹ (aromatic C = C), confirming PAH-related functional groups. Cluster analysis demonstrated distinct grouping of sampling environments, with indoor samples separating from outdoor and junction locations. Toxicological classification identified carcinogenic, genotoxic, and teratogenic PAHs. Non-carcinogenic risk was low, with Hazard Index values (0.0043–0.0084) below the U.S. EPA threshold (HI < 1). Incremental lifetime cancer risk was higher in children than adults and largely within the U.S. EPA acceptable range (10⁻⁶–10⁻⁴). Conclusions The study revealed the occurrence of PAHs and associated functional groups in deposited dust from hospital environments. Health risk assessment showed that non-carcinogenic risks were within acceptable limits, while cancer risks, particularly for children, were of potential concern. These findings show the need for improved dust management, ventilation, and pollution control strategies in healthcare facilities to reduce chronic PAH exposure.