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1. Background Radiation

   Linked via "Guarapari, Brazil"

   Potassium-40 ($\text{K}-40$), present in trace amounts in common materials such as concrete, soil, and even biological matter, contributes significantly through beta decay. Its relatively long half-life ($1.25 \times 10^9$ years) ensures its steady presence.
   The intensity of terrestrial background radiation is heavily dependent on local geology. Regions characterized by granite intrusions or sedimentary depos…