Indoor Radon Research conducted in South Africa from 1980s – To date ( 2019 ): A Review
* Atsile Ocwelwang 1 , 2 , Cynthia Sethabela 2 , Manny Mathuthu 2 , Paballo Moshupya 1
1 Centre for Nuclear Safety and Security ( CNSS ), National Nuclear Regulator ( NNR ), Eco Glades 2 Block G , 420 Witch Hazel Avenue , Highveld , Centurion . PO Box 7106 Centurion , 0046 .
2
Centre for Applied Radiation Science and Technology , North-West University ( NWU ) – Mafikeng Campus , Corner of Albert Luthuli and University Drive Mmabatho . Private Bag X2046 Mmabatho , 2745 .
* Corresponding author ’ s email : aocwelwang @ nnr . co . za
Abstract . The history of research on radon and indoor radon measurements in South Africa ( SA ) dates back to the mid-1980s and early 1990s . Small-scale studies have been performed in areas where high radon concentrations were expected due to the geology and the mining history of the area . Most of these studies were performed in Gauteng and Western Cape provinces . Gauteng province has a long history of gold mining and this has left behind large amounts of waste that contain long-lived naturally occurring radionuclides such as uranium-238 ( 238 U ) which decays into radium-226 ( 226 Ra ) from which radon-222 ( 222 Rn ) emanates . Radon research conducted in the Western Cape Province was mainly due to the geology of this region , which is rich in granitic rocks . This study reviews published journal articles and reports on indoor radon measurement studies conducted across the country to establish a baseline data for the current study , which focuses on the development of a national radon survey and radon mapping strategy in SA . Moreover , findings made in this desktop review will inform the development of the national indoor radon database and the establishment of a regulatory framework for radon in dwellings and other buildings with high occupancy by members of the public .
KEYWORDS : Radon progeny ; Indoor Radon ; NORM ; Uranium , Mining impact ; Regulatory Framework .
1 INTRODUCTION Radon-222 ( 222 Rn ) is a naturally occurring , inert radioactive gas that is produced directly from the alpha decay of the long-lived ) radium-226 ( 226 Ra ) along the radioactive decay chain of uranium-238 ( 238 U ). This radioactive gas is colourless and odourless , it cannot be detected by human physical sense and has a half-life of 3.82 days [ 1 ]. For many years it was believed that only underground mines have a high level of radon and mine workers are the only individuals that have significant radon exposure [ 2 ]. Many international studies have proven that occupants of above-ground workplaces and residences around gold or uranium mines and geological regions with high granitic content can also be exposed to high levels of radon that exceed the recommended levels [ 3 ].
Radon is by far one of the major contributors of radiation exposure to the public , including exposure in homes worldwide [ 4 ]. Inhalation or ingestion of radon progenies has proven to cause damage to the deoxyribonucleic acid ( DNA ) molecule of a cell and to induce lung cancer [ 5 ]. Reports by the International Agency for Research on Cancer ( IARC ) have confirmed that long-term exposure to radon and its short-lived decay products , polonium-218 ( 218 Po ) and polonium-214 ( 214 Po ) causes lung cancer in humans [ 3,6 ]. Studies on the health effects of radon in underground workplaces began several decades ago , the focus was extensively on uranium mineworkers . However , in the late 1970s and early 1980s , radon studies began to include measurements and surveys of radon gas concentration in private homes and other buildings with high occupancy factors for the public [ 7 ]. It is thus very important to conduct indoor radon measurements to assess the extent of human exposure to radon in dwellings and other public buildings with high occupancy by the public .
South Africa ( SA ) has a legacy of more than 100 years of gold mining ; whereby gold along with uranium has been mined from the largest gold reefs of Witwatersrand since 1886 . The Witwatersrand ( Wits ) Basin includes Central Rand Basin , Eastern Basin , Western Basin , Far West Basin , the Free State
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