## 3 Materials and Methods
It is assumed that at the beginning of a project of this nature, the geographic limits of the region to be analyzed are defined in advance, as well as the existence of the necessary data for the continuation of the work being confirmed. The information necessary for the elaboration of the platform is gathered and analyzed, namely the information that will serve as the base map, which can be a georeferenced satellite image or a georeferenced geographic map, which allows citizens to f  
Figure 1: Flowchart of the methodology for radon potential mapping. they want to obtain information on the radon potential level. Additionally, in this phase, information is collected on geology, administrative boundaries, and any other available information that contributes, first, to increase the reliability of the results, and second, to contribute to the meeting of the real needs of users. Finally, still in this phase, and after obtaining the natural gamma radiation map of the region under analysis (or where the region under analysis falls), a detailed analysis is carried out, so that the criteria for the definition of radon potential is put forward. This question is of particular importance, as it will be based on this definition that the boundaries between the different radon potential areas will become more or less accurate. In other words, in the case of doubt, it is preferable to have a false positive, which is later confirmed with a traditional radon assessment, instead of having a false negative that leaves occupants exposed to an increased concentration in an unprotected and incautious scenario. The last operation of this phase is the compilation, analysis, and preparation of the platform, in which, after defining the order of the information layers (base map, geology map and natural gamma radiation map), the radon potential map is prepared. This construction of the map is based on the definition of boundaries between areas with different radon potentials and following the previously defined categories. For example, three radon potential categories can be chosen, such as being low, medium, or high, but an even larger one can be chosen in the more detailed subdivision, such as very low, low, medium, high, and very high. However, this division must be made according to the scale provided by the natural gamma radiation map and always in such a way to allow the radon assessment to lean towards the detection of false positives instead of false negatives. In Phase I, which can be considered the awareness and engagement phase, focusing on the implementation, the access of potential users to the platform and information is prepared, which must be made available in a perspective of pre-diagnosis assessment through a user-friendly interface, which can be accessed by anyone, even for those with shorter digital skills. This platform provides a website with information about radon so that the user can make an informed use, and where they can clarify doubts on the subject. It is an interactive tool that returns the level of geogenic radon potential at a given location to the citizen, including generic mitigation recommendations. In cases of high level of radon potential, the citizen is proposed to carry out the assessment in the building/compartment, presenting the contact details of entities that can carry out this assessment by experts. That is, it will provide the user with the recommendation defined in the radon potential categories, which must point to the need, or not, to technically assess the indoor radon concentration, also through a combination of other factors, namely the existence, or not, of permanent occupancy of the building. At this stage, the user is asked to register when they want to check the radon potential in a certain location. With this information, which is optional, the user will be able to receive project updates. Phase II corresponds to the development and implementation of the potential radon estimation model, with a focus on buildings.