Abstract

The unregulated activities of a scrap iron and steel smelting industry in Lagos, Nigeria necessitated the sampling of particulate matter (PM₁₀ and PM_2.5) particles from various sections of the industry. The samples were analyzed using polarized energy dispersive x-ray fluorescence (EDXRF) technique which allowed the simultaneous detection of over 25 elements in each of the samples. The mass concentration levels ranged from 86 to 8765 µg/m³ for PM₁₀ and 10 to 462 µg/m³for PM_2.5. The highest concentrations of 8765 and 462 µg/m³ for PM₁₀ and PM_2.5, respectively, were observed at one of the electric arc-furnaces (EAF-2). This was attributed to the scrap smelting and additives used. The observed high concentrations of PM₁₀ lead (Pb) at various sites, when compared with exposure limit of between 1.0 and 5.0 µg/m³ set by Occupational safety and Health Administration (OSHA) and United State Environmental Protection Agency (US EPA) is emphasized. For zinc (Zn), the measured levels exceeded the OSHA workplace occupational exposure limit set at 1 mg/m³ for an 8-h workday over a 40-h work week and that set by the National Institute for Occupational Safety and Health (NIOSH) for up to a 10-h workday over 40-h workweek. These results suggest the need for immediate repair or replacement of the emission control devices.

Key words: PM₁₀, PM_2.5, polarized EDXRF, toxicity potential, electric arc-furnace, turboquant.