Characteristics and Risk Assessment of Heavy Metals in Airborne PM10 from a Residential Area of Northern Jeddah City, Saudi Arabia

This study was carried out in order to investigate the seasonal distribution of PM10 and its heavy metals contents in the atmosphere of a residential area of northern Jeddah during 2011-12. Potential health risk assessment for heavy metals exposure was assessed. The concentrations of 15 elements, including Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Sr, Cd, and Pb in PM10 were determined using x-ray fluorescence. The annual average concentration of PM10 (65 mu g/m(3)) was much higher than the WHO standard for PM10 (20 mu g/m(3)). Concerning the frequency distribution of 24-h concentration of PM10, about 29%, 20%, 86%, 71%, and 54% of the mean 24-h concentration of PM10 during summer, autumn, winter, spring, and the whole year, respectively, exceeded the WHO air quality standards for maximum 24-h concentration. Dust storm events are the main reason for the highest PM10 concentrations in winter and spring. The sum of metal concentrations in PM10 was 4,327 ng/m(3), representing 6.66% from particulate mass during the period of study. Fe and Al were the dominant metals, followed by Ti, Mn, Cd, Zn, Sr, V, Cu, Pb, Ni, Co, Cr, As, and Ga. The sum of metal concentrations was found to be higher in winter followed by spring, summer, and autumn. The annual Ni and Cd levels in PM10 were higher than the proposed WHO, U.S. EPA, and the European Community standards. The enrichment factors (EFs) values and non-crustal fractions indicate that Cd, As, Pb, Zn, Co, V, and Cu are mainly emitted in the atmosphere of the study area from anthropogenic sources. Based on the average values of As, Cd, Cr, and Ni in PM10, Cd was found to have the highest excess cancer risk. Total ECR resulting from exposure of these carcinogenic metals through inhalation pathways was 108.77. These results indicate that 108.77 people out of 1 million are at risk of developing cancer after exposure to the carcinogenic trace metals in ambient airborne PM10 from a residential area of northern Jeddah.