Visualizing radiofrequency electromagnetic field exposure through Voronoi-based maps

Measuring the exposure of radiofrequency electromagnetic fields in a city is a very laborious task. To simplify this process for a city of 200 thousand inhabitants, Voronoi diagrams were used. The city was divided into cells based on the Euclidean distance to a point on the map, and each cell was assigned the value of the electric field measured at that point using a personal exposimeter. The number of cells varied from five to 30 and, finally, one 100. The maps obtained are commented on, using a palette of four uniform colors for the cells, to facilitate their perception. The more cells are considered, the smaller the cells will be. A stabilization of the process is observed as the points within the city map increase. The colors represent the RMS (root mean square) electric field measured at each seed point, extended geometrically to its Voronoi cell for visualization purposes. The colors of the areas remain the same; and in some other areas, cells appear with slightly distinct colors, due to the addition of new measured points. Some cells change color due to these new measurements of the new points. In this study, the predominant color is green, which is the measured field at the seed point was 1.9 V/m RMS (while the maximum allowed by the ICNIRP guidelines is 61.4 V/m). There are three cells in the city with E values above 3.9 V/m, reaching the highest value of 11.4 V/m. The entire city is within the recommended maximum. The Voronoi diagram method is shown to be useful and interesting for the presentation of radiofrequency electromagnetic fields exposure measurements in a medium-sized city. The Voronoi cells do not contain information about the intracell spatial variation of the electric field; each polygon represents the RMS value measured at its generating point (seed), offering a discrete visualization of the spatial distribution of the measurements and illustrating how the electric field levels vary across the study area.