People have always been exposed to natural radiation, be it from external sources (cosmic or earth radiation) or from internal exposure through the intake of radioactive elements (radionuclides) via the respiratory system and the food they eat.
As with many other things, it depends on the dose. Today, we are able to measure this radiation and, for instance, to compare the exposure rate produced by house building materials with the limit value recommended by the International Commission on Radiological Protection (ICRP). This also allows us to find out if the measured values exceed the average exposure rate existing in a certain region