[en] After the end of the radioactive fallout, in the beginning of the post-accidental stage, it should be possible to take decision to implement actions to reduce contamination in urban environments. The principal aim of these actions is to improve the radiological situation of the environment and thereby reduce the exposure of the population that will stay there. None of these actions wilt restore the environment to its initial condition. The second objective is to demonstrate that the situation has been anticipated and properly controlled. In the first days, it must be possible to take decisions to implement some emergency actions without stakeholder consultation. The main actions concern washing of hard surfaces such as roads, waits and roofs. To implement heavy-duty actions (stripping, replacement of roofs, covering of surfaces, etc.), a framework for discussion and exchange of information between all parties should be set up to look at the value and optimisation of these actions. (author)