Contamination levels, health risks and source apportionment of in-vehicle and park dusts potentially toxic elements (PTEs) in Abuja, Nigeria

Abstract

Introduction: The rapid urbanization and heavy traffic in cities raise concerns about health and environmental risks from Potentially Toxic Elements (PTEs). This study analyses the levels of contamination, origins, and exposure hazards of 10 PTEs (Fe, As, Cd, Zn, Cu, Mn, Pb, Cr, Co, Ni) in dust from five public vehicles and five motor parks in Abuja, Nigeria. Materials and methods: Digested samples of park dust were analysed for Fe, Pb, Zn, As, Co, Cr, Cu, Cd, Mn, Ni (ten PTEs) using Atomic Absorption Spectrophotometer (AAS). PTE sources were ascertained using Positive Matrix Factorization (PMF) alongside contamination indicators comprising of Enrichment Factor, Geo-accumulation Index, Contamination Factor and Ecological Risk Factor. A new pollution indicator, the Nemerov Integrated Risk Index (NIRI), was evaluated for consistency with existing methods. Exposure risks (cancer and non-cancer causing) were assessed for commuters. Results: PMF revealed five PTE sources: brake/engine wear (50%), vehicular body wear (1%), tyre wear/lubrication leaks (12%), coal combustion (6%), and vehicular emissions (31%). Cd exhibited the highest contamination levels across all indices. NIRI results aligned with traditional indices, confirming severe Cd pollution. Health risk assessments showed insignificant non- carcinogenic and carcinogenic risks for adults and children, though children were more vulnerable. Conclusion: Traffic-related activities were the dominant sources of PTEs in Abuja’s vehicle and motor park dusts. Cadmium (Cd) exhibited the highest enrichment, exceeding background levels and posing high ecological risk particularly for children, while other PTEs presented low health risks. This study underlines the necessity for targeted mitigation and non-stop monitoring to reduce PTE exposure in urban transit environments.