The generation of nanoparticles at concentrations sufficient to perform toxicology studies is highly challenging. The vaporization/condensation technique has successfully been used previously to generate nanoparticle aerosol. However, the maximum mass concentrations generated were low (similar to 0.180 mu g/L), and the generation method produced aerosol having a mixed chemical composition. In this study, a new, dynamically operated, nanoparticle generation system has been developed that generates nanoparticles having a count median diameter of 40-60 nm and continuously delivers a mass concentration as high as 2 mu g/L at the nose exposure port of a nose only exposure system. This system generated nanoparticles by using an inline tube furnace for flash vaporizing micron-sized particles fed continuously from an aerosol generator. This paper describes both the experiments and the operating conditions used for generating nanoparticles to demonstrate the system's capability and the methods used for physicochemical characterization of the resulting nanoparticles. (c) 2007 Elsevier Ltd. All rights reserved.