Occupational Health Risks from Metal Dust Exposure in Nigerian Metal Fabrication Workshops: A Materials Engineering Perspective

This study examines occupational health risks associated with metal dust and fume exposure in medium-sized metal fabrication workshops in Kaduna State, North West Nigeria, from a materials engineering perspective focused on dust characterisation and engineering control effectiveness. Occupational respiratory disease linked to metal dust inhalation is a significant but under-documented health burden in Nigeria's informal and semi-formal manufacturing sector, and the chemical and physical characterisation of workshop dusts is a necessary step toward evidence-based exposure reduction. Airborne dust samples are collected using personal and area samplers from twelve workshops in Kaduna metropolitan area during grinding, welding, and thermal cutting operations. Collected samples are analysed by SEM-EDX, ICP-OES, and FTIR for particle morphology, elemental composition, and crystalline silica content. Airborne metal concentration levels are compared against the Nigeria Occupational Safety and Health Regulations permissible exposure limits. Current engineering controls including local exhaust ventilation, enclosures, and personal protective equipment provision are audited. Findings reveal that 8 of 12 workshops have airborne manganese concentrations exceeding the 0.2 mg/m3 NIOSH recommended exposure limit during welding operations. Iron oxide and chromium fume levels exceed guideline values in 4 workshops. Local exhaust ventilation is present in only 3 facilities and rated as adequate in 1. Keywords: metal dust, occupational health, fabrication workshop, Kaduna State, exposure assessment.