Evaluation of lead concentration over Tehran metropolitan area

Considering the traffics volume in Tehran, the lead measurement in city's atmosphere is of prime important. The source of lead in cities atmosphere is either in inorganic fonn, resulting from combustion of leaded gasoline, or in organic form, from unburned evaporated gasoline. For the first time in Iran a procedure was adopted for organic lead determination in air by the department of air pollution in Research Institute of Petroleum Industry (RIPI). The determination of lead in air, organic and inorganic, were carried out in five locations for the period ofnine months. The results indicated that concentration of inorganic and organic lead ranged respectively from 0.24 to 3.4 $\mu$g/m$^3$ and Trace amount to 15.15 $\mu$g/m$^3$ as Pb. Concentrations were generally highest in densely traffic areas, intermediate in commercial areas, and lowest in residential areas. The effect of inversion phenomena and metrological parameters were the main reasons for increasing of average lead concentrations in autumn and winter