The aim of this study was to investigate the in vitro cytotoxicity and inflammation of human bronchial epithelial cells (BEAS-2B) after exposure to various type and size of nanoparticles (NPs).We measured the cell viability and the release of the proinflammatory cytokines IL-6 and IL-8 by BEAS-2B treated with manufactured nano-sized particles of Ag,Au,Fe2O3,TiO2,and CNT.The cell viability was dose-dependently reduced for all materials except Au.The cytotoxicity of Ag and MWCNT was increased due to their smaller size (< 50 nm).Although the cell death by 50nm Fe2O3 was not observed,that of 15nm Fe2Oa was one of the most.