Over the past several years concern over the physiological and biochemical effect of inhaled oxidants on the lung has increased rapidly. Two of the most dangerous oxidizing agents present in the urban environment are ozone and the oxides of nitrogen, especially nitrogen dioxide. Exposure to relatively high concentrations of NO2 or ozone produces serious and often fatal lung damage. We plan to develop an in vitro system (which is relevant to an in vivo situation) for assessing the toxicity of oxidant air pollutants and to utilize this system to learn more about the effects of air pollutants at the cellular and subcellular level. We will employ a range of assays to detect degrees of damage ranging from very subtle changes in cell function to outright cell death. We will also investigate the feasibility of utilizing antioxidants as protection against the deleterious affects of these agents. We will investigate the role of lipid peroxidation, enzyme inactivation and resynthesis and DNA damage in cellular toxicity due to air pollutants.