Occupational exposure to nanomaterials in manufacturing plants may pose serious health risks, and the industrial production rate of small size particles is growing exponentially. An estimated 745,000 workers are potentially exposed to engineered nanoparticulate matter in the manufacturing sector alone; within 10 years, that number is expected to increase to more than 1 million workers. Both human and animal studies have associated exposure to metals with a range inflammatory diseases, especially within the lungs (asthma, fibrosis and COPD). Toxicity of metals has been studied for a long time, however, the toxic potential of nanometal oxides, that are being produced in large scale due to their use in a wide variety of industrial applications, is not clear. Exposure pathways, resultant bioavailability, and potential adverse health outcomes of these metal nanoparticles in humans are poorly understood. This proposal will focus on physicochemical characterization, transport, biological response and occupational exposure of engineered nanometal oxides. Our specific aims are 1) Characterization of biological response, transport and physicochemical properties of metal oxides and 2) Pilot assessment of exposure and characterization of physicochemical properties of metal oxides in exhaled breath of exposed workers. The proposal involves a strong interdisciplinary collaboration between experts on exposure assessment, aerosol science, nanotechnology, the protective mucus barrier, pulmonary molecular toxicology, and a company focused on the large scale production of nanometal oxides (NanoProducts Corporation). Overall these studies will help in understanding the potential risk of nanometal oxides to human health and also develop the knowledge base required for future studies on a larger populations exposed to nanometal particles. Supplemental key words: Nanometal oxides, exposure assessment, physico-chemical properties, mucus transport, biological affects, human lung cells