Radon in dwellings and workplaces: An update on current regulations

摘要

Uranium (~(238)U), with a half-life of 4.5 × 10~9 years, and thorium (~(232)Th) are the primordial radionuclides present in the earth and rocks. ~(238)U decays to form a series of radionuclides, with the decay chain ending with stable ~(206)Pb. ~(226)Ra (half-life - 1600 years) is one of the radiotoxic radionuclides in the ~(238)U series. These naturally occurring radionuclides form a continuous source of gaseous progeny radionuclides — radon (~(222)Rn) and thoron (~(220)Rn from ~(232)Th series). Radon, with a half-life of 3.82 days, is the gaseous radionuclide, which is the major natural source of radiation exposure of the world's population. Radon is ubiquitous and its concentrations in the environment, including dwellings, vary from place to place depending on the level of its parent radionuclide, ~(226)Ra. According to the WHO, indoor radon exposure poses a significant public health hazard. Within the system of protection, exposure to unmodified naturally occurring radionuclides has characteristics of the existing exposure situations.