Effects of the roadside atmosphere were investigated by placing pots of lettuce plants (Lactuca sativa L. cv Romaine) along a transect representing different levels of urbanization in Jeddah city, Saudi Arabia. Concentrations of elements in soil samples, foliage dust, and leaves of lettuce collected from rural, urban, suburban, residential, and industrial areas were analyzed for Ni, Pb, Co, Zn, V, Sb, As, Cu, Cr, K, Mg, Ca, Fe, Al, and Na. We found higher concentrations of these elements in the urban and industrial areas than in the other areas. These high concentrations could be attributed to traffic sources and depend on traffic and urbanization levels. Lettuce plants can be used as bioindicators to determine the effects of air pollution in the atmosphere of the city. It is necessary to monitor toxic metals for plants used for human consumption.