When studying the toxicological effects of pollutants, mostly this is achieved examining their action one at a time whereas in real life, many pollutants act together in a given period of time. This is well known as the cocktail effect. In addition, the close interactions between numerous physico-chemical and toxicological effects are not always scrutinized. In this framework, the TOXinTRANSPORT project was set up. It aimed at examining in-depth the close relationship between the physico-chemical and toxicological effects and the way the former impacts the latter. The context was that of railway transport where this link between physico-chemistry and toxicology was made. Numerous instruments were used to determine the physico-chemical properties of two environments, namely an underground platform and a railway rolling stock. This characterization was made along with toxicological analyzes. The originality of this project was to resort to a biosampler to collect aerosols prior to toxicological analysis. This eliminates the tedious step of filter processing, technique usually used for sampling. Among the main results, toxicological effects have been linked to the presence of certain physico-chemical parameters and their concentration levels. Inflammation seems to be linked to high concentrations of metals (particularly iron). The obtained results are presented and discussed.