IMPACTS OF TRAFFIC-INDUCED LEAD EMISSIONS ON AIR, SOIL AND BLOOD LEAD LEVELS IN BEIRUT Z. HASHISHO and M. EL-FADEL ∗ Faculty of Engineering and Architecture, American University of Beirut, Lebanon ( ∗ author for correspondence, e-mail: mfadel@aub.edu.lb) (Received 17 June 2002; accepted 9 May 2003) Abstract. Lead is a purely toxic heavy metal which induces a wide variety of adverse physiologic effects. Nevertheless, it has been mined and used for more than 8,000 years. Among the different contemporary sources of lead pollution, traffic-induced emissions from the combustion of leaded gasoline is of particular concern, as it can constitute more than 90 percent of total lead emissions into the atmosphere in congested urban areas where no phase-out activities have been adopted. Gasoline lead content and traffic volume are strongly correlated with concentrations of lead in various environmental media. In the absence of policies to reduce the use of lead in gasoline or to favor the use of unleaded gasoline, leaded gasoline remains the predominant grade in many countries. This paper assesses the status of lead pollution from the combustion of leaded gasoline in Beirut based on field measurements of lead in air and roadside dust of urban and rural/suburban areas and recent data on soil and blood lead levels. Average atmospheric lead concentrations was about 1.86 µgm −3 at urban locations and 0.147 µgm −3 at suburban locations. The analysis of roadside dust revealed an average lead level of 353 µgg −1 along urban streets and 125 µgg −1 along rural/suburban roads Blood lead levels were also relatively high in comparison to countries where leaded gasoline has been phased-out. Keywords: lead pollution, leaded/unleaded gasoline, traffic-induced emissions 1. Introduction Air pollution is one of the most significant environmental problems worldwide particularly in urban areas. While natural sources can contribute to this problem, anthropogenic sources are often the main contributors with mobile sources contrib- uting up to 90 percent of total emissions depending on location and environmental policies. Among the various vehicle-induced pollutants, lead is of particular con- cern because it indirectly affects all organs in the body by interfering with different enzyme systems (WHO, 1987). The adverse physiologic effects of lead resulted in the development of standards for lead levels in the air and blood (Table I). The standards for blood lead levels have been continuously reduced as emergent studies provided new toxicological and epidemiological evidences revealing the inadequacy of previous standards. While regulatory agencies and health organizations have all reduced the amount of lead considered to cause lead poisoning, they have not reached a firm consensus on the maximum permissible concentration of lead in blood (He, 1996). In fact, there Environmental Monitoring and Assessment 93: 185–202, 2004. © 2004 Kluwer Academic Publishers. Printed in the Netherlands.