Radon (or Rn-222) is a naturally occurring radioactive noble gas with a half-life of 3.8
days resulting from the decay of radium (Ra-226) (uranium-radium series). In the further decay chain
arise as follow-on nuclides the short-lived alpha emitters Polonium (Po-218), Polonium (Po-214)
and the beta emitters lead (Pb-214) and bismuth (Bi-214), which bind to dust particles and the largest
part of the inhalation-related radiation exposure. Particularly important for indoor radon
is the penetration of radon from the natural soil. This is particularly the case with
houses with poor isolation from the ground. Anomalies caused by building materials usually have one
subordinate meaning and are only relevant in individual cases.