Energy and material audit, measurement of concentration of suspended particulate matter (SPM) and elemental analysis of the SPM were carried out in a scrap iron and steel smelter in Lagos, Nigeria. This was with the view to assessing the operational efficiency and to determine the occupational exposure of workers in various production processes of the industry to toxic heavy metals. Size segregated suspended particulate matter-PM10(respirable fraction), PM2.5 (inhalable fraction) and TSP (Total suspended particulate) were collected. A combination of Total Reflection X-ray Fluorescence (TXRF), Polarized Energy-Dispersive X-ray Fluorescence, Induced Couple Plasma Optical Emission Spectrometer (ICP-OES) and Conventional EDXRF techniques were used for the elemental analysis of the collected sample. The study concluded that TSP was above the WHO guidelines and the Federal Ministry of Environment (FMEmv) Nigeria for industrial environment at all location and that activities in the production section contributed significantly to the concentrations of heavy metals in the ambient air within the factory.