detect the presence of radon gas in the subsoil before building new buildings - concept with an imaginary city map

air pollution surveyor cadastral cadastre radon test radiation radioactivity risk danger gas dangerous radium radioactive contamination construction industry building activity residential district city street town urban map plan planning green area rural scene hand writing drawing concept concepts ideas lawn meadow grass field nature land countryside human agriculture outdoors cartography topography suburb road detect presence subsoil before new buildings imaginary territory fields roads against text