What are the risks for the personnel following a gas leak in a laboratory? How effective are the safety measures (gas detection) put in place? Are users aware of how fast they can be exposed? These questions have been approached with the intent to better communicate to the users the risks involved in their daily activities by showing how a gas is dispersed in their laboratory. In order to do so, a software tool performing Computation Fluid Dynamics (CFD) simulations of a pollutant gas dispersion in a room has been developed by the Chemical and Physical Safety Group (GSCP) at EPFL in collaboration with Optimad Engineering srl. The software and its physical model have been based on experimental data obtained by the GSCP used as a benchmark for the numerical simulation results. As side deliverables, these results are been used to place gas leak detectors in the most efficient location, thus optimizing the cost of safety measures. Furthermore, the simulation results have then been used to create videos showing the pollutant gas dispersion in the laboratory. A real case is presented in order to reveal the power of the used dual methodology: modelling as a mean of communication for an effective training/teaching of the personnel. The visual representation of the risks has a greater impact than any other means of communication available