In this study an in vitro exposure test to investigate toxicological effects of the volatile disinfection by-product trichloramine and of real indoor pool air was established. For this purpose a set-up to generate a well-defined, clean gas stream of trichloramine was combined with biotests. Human alveolar epithelial lung cells of the cell line A-549 were exposed in a CULTEX® device with trichloramine concentrations between 0.1 and 40 mg/m3 for 1 h. As toxicological endpoints the cell viability and the inflammatory response by the cytokines IL-6 and IL-8 were investigated. A decreasing cell viability could be observed with increasing trichloramine concentration. An increase of IL-8 release could be determined at trichloramine concentrations higher than 10 mg/m3 and an increase of IL-6 release at concentrations of 20 mg/m3. Investigations of indoor swimming pool air showed similar inflammatory effects to the lung cells although the air concentrations of trichloramine of 0.17 and 0.19 mg/m3 were much lower compared with the laboratory experiments with trichloramine as the only contaminant. Therefore it is assumed that a mixture of trichloramine and other disinfection by-products in the air of indoor pool settings contribute to that effect.