In a series of investigations, an experimental system was established for the study of the interactions of environmentally relevant gaseous compounds and cultured cells. The aim of this study was the development of culture conditions which allow the direct exposure of cells to gaseous compounds at the air/liquid interface for the evaluation of dose-dependent biological effects. The project also aimed at providing the gaseous test substances at concentrations in the sub-vpm region. To achieve these aims, an experimental culture and exposure system was developed which consisted partly of a gas reaction chamber (24001) to provide the possibility of irradiating the gas mixture. The gaseous compounds were conducted to a perspex chamber (3.5 l) in which the cells growing on transwells were exposed. Analysis of the gaseous compounds was performed at the inlet and outlet of the exposure chamber. To assess the cytotoxicity, the following biochemical markers were determined: amount of dsDNA, WST, BrdU, LDH in culture medium and the activity of glutathione-S transferase and esterases. Using this system, dose-dependent cytotoxicity or strong cytotoxic effects were established for ozone (200-900 vpb), PAN (peroxyacetyl nitrate, 20-200 vpb) and NO₂ (80-360 vpb). Exposure to purified air did not show significant effects. In addition, some irradiated gas mixtures showed cytotoxicity whereas non-irradiated mixtures did not.