Characterization and Risk Analysis of Metals Associated with Urban Dust in Rawang (Malaysia)

This study was designed to determine the particle size distribution and develop road dust index combining source and transport factors involving road dust for dust pollution quantification in Rawang. Principal component analysis (PCA) was applied to identify possible sources of potentially toxic elements and spot major pollution areas in Rawang. The health risks (carcinogenic and noncarcinogenic) to adults and children were assessed using the hazard index and total lifetime cancer Risk, respectively. A total of 75 road dust samples were collected and particle sizes (1000, 500, 250, 160, 125 and 63 µm) were determined. Concentrations of potentially toxic elements (Cu, Cd, Co, Cr, Pb, Ni, Zn and As) in particle size of 63 µm were analyzed. The results demonstrated that the highest grain size of 250 µm has contributed almost more than 25% of atmospheric particulate pollution. The highest potentially toxic element concentration was Pb (593.3 mg/kg), whereas the lowest was Co (5.6 mg/kg). Road dust index output indicated that pollution risk fell into moderate levels in eastern and northern areas of Rawang. Similarly, PCA results revealed that potentially toxic elements (Cu, Cd, Pb, Zn, Ni and Cr) were linked with anthropogenic sources (urbanization process, industrial and commercial growth, urban traffic congestion) in northern and southern parts of Rawang. Cobalt and As concentrations were explained mainly from natural sources. Noncarcinogenic risk by hazard index value more than 1.0 was indicated for adults and children. Similarly, carcinogenic risk by total lifetime cancer risk value also showed carcinogenic risks among adults and children.