Natural radioactivity and radiological hazard for humans: a simple introduction for newbies and students. New perspectives and innovative teaching methods

Pollution due to natural radioactivity is still a poorly known topic among young people. This paper describes the contents for an introductive university course or lecture conceived in a multitask program. Along with a so-called “flipped” configuration, where students are able to receive didactic materials prior to face-to-face lessons, multimedia contents should be shown to the students, who are at first faced with known anthropogenic accidents. Moreover, field and laboratory experimental activities can provide further insight regarding the radiological assessment strategies. Here, the most important principles and effects concerning the radioactive decay of naturally occurring radionuclides are described. The greatest part of natural radioactivity derives from terrestrial radionuclides occurring in soil and rocks. The radionuclides are atoms characterized by an excess of nuclear energy, which makes them unstable giving rise to decay. The radionuclides emit gamma rays, as well as alpha and/or beta particles. People are constantly subjected to indoor and outdoor exposure due to natural radioactivity. The possible sources can be considered as external due to natural sources located outside the human body, and internal provoked by ingestion or inhalation of radionuclides. The indoor exposure from natural sources is mainly related to radiation from building materials and to radon entering buildings from soils and rocks though cracks in walls and floor. The outdoor exposure mainly accounts for the terrestrial gamma radiation that crosses the soil-air interface, and for the radon emitted from soils in seismic and volcanic areas. In this regard, there is a strong relationship between health diseases (e.g. cancer, necrosis and DNA and RNA modifications) and high-levels of natural radioactivity. For this reason, the radiological assessment of the most vulnerable areas represents a key point in order to mitigate hazard and risk connected to the human exposure to natural radioactivity.