Measurement of radioactivity in the environment - Air: Radon-222. Pt. 9: Test methods for exhalation rate of building materials (ISO 11665-9:2019)

Radon isotopes 222, 219 and 220 are radioactive gases produced by the disintegration of radium isotopes 226, 223 and 224, which are decay products of uranium-238, uranium-235 and thorium-232 respectively, and are all found in the earth's crust. Solid elements, also radioactive, followed by stable lead are produced by radon disintegration. When disintegrating, radon emits alpha particles and generates solid decay products, which are also radioactive (polonium, bismuth, lead, etc.). The potential effects on human health of radon lie in its solid decay products rather than the gas itself. Whether or not they are attached to atmospheric aerosols, radon decay products can be inhaled and deposited in the bronchopulmonary tree to varying depths according to their size. Radon activity concentration can vary from one to more orders of magnitude over time and space. Exposure to radon and its decay products varies tremendously from one area to another, as it depends on the amount of radon emitted by the soil, weather conditions, and on the degree of containment in the areas where individuals are exposed. DIN ISO 11665-9 (VDE 0493-1-6659) specifies a method for the determination of the free radon exhalation rate from building materials (radon-222). Any contribution of thoron (Radon-220) to the measurement result is neglected when the described method is applied. Responsible is the DKE/GK 851 "Activity measuring instruments for radiation protection" of the DKE German Commission for Electrical, Electronic & Information Technologies in DIN and VDE.