*Article* **A New Methodology for Defining Radon Priority Areas in Spain**

**Alicia Fernández, Carlos Sainz, Santiago Celaya \*, Luis Quindós, Daniel Rábago and Ismael Fuente**

Environmental Radioactivity Laboratory of the University of Cantabria (LaRUC), University of Cantabria, Santander, 39011 Cantabria, Spain; alicia.fernandezv@unican.es (A.F.); sainzc@unican.es (C.S.); luis.quindos@unican.es (L.Q.); daniel.rabago@unican.es (D.R.); fuentei@unican.es (I.F.)

**\*** Correspondence: santiago.celaya@unican.es

**Abstract:** One of the requirements of EU-BSS (European Basic Safety Standards) is the design and implementation of a National Radon Action Plan in the member states. This should define, as accurately as possible, areas of risk for the presence of radon gas (222Rn) in homes and workplaces. The concept used by the Spanish Nuclear Safety Council (CSN), the body responsible for nuclear safety and radiation protection in Spain, to identify "radon priority areas" is that of radon potential. This paper establishes a different methodology from that used by the CSN, using the same study variables (indoor radon measurements, gamma radiation exposure data, and geological information) to prepare a radon potential map that improves the definition of the areas potentially exposed to radon in Spain. The main advantage of this methodology is that by using simple data processing the definition of these areas is improved. In addition, the application of this methodology can improve the delimitation of radon priority areas and can be applied within the cartographic system used by the European Commission-Joint Research Center (EC-JRC) in the representation of different environmental parameters.

**Keywords:** radon potential map; geography information systems; geology; risk
