This study dealt with the impact of air pollution an the integrity of cell membranes in the lichen Ramalina duriaei. The lichen was transplanted from a relatively unpolluted site in Israel to more polluted sites, adjacent to a 40-year-old town, for a period of 10 months. The concentrations of K, B, Al, Cr, Fe, Si, Ti. Zn, P, Be, Cu, Mg, Na, Pb, Ca, Mn, Sr, and S in lichen thalli were compared with injury: caused to the cell membranes. The study indicates that electric conductivity reflects adequately cellular injury to lichen thalli transplanted to sites near a motorway, an oil-fueled power plant and a rural community: (a kibbutz). The concentrations of S, B, Al, Cr, Fe, Si, Ti. and Zn correlated with injury in cell membranes of R. duriaei retrieved from the biomonitoring sites, whereas the concentration of K in the thalli correlated inversely with the electric conductivity parameter. Leakage of K fro;from lichen thalli as a result of air pollutants is suggested. This K leakage correlates positively with concentrations of S and Cr in transplants of R. duriaei to the Ashdod region.