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===Health effects of radon gas===

===Health effects of radon gas===

Radon is a colourless inert gas formed from the radioactive disintegration of radium –the radioactive daughter of uranium. It has been established that there is a link between the levels of radon emitted by the rocks and that emitted by soils. The level of radon emitted by any rock depends on the quantity of uranium it contains which occurs in association with other minerals such as gold, phosphate and copper. This explains the scourge of lung cancer amongst uranium miners, as radon is carcinogenic. Radon emitted from most rocks travel to the surface through fractures and faults (Finkelman et al, 2010b). Its movement into buildings occurs through foundation cracks, cracks in the floor and walls below and above the surface. It can also enter through gaps in timber floors and around pipe fittings (Fig. 10).

[[File:UNN_Medical_Geology_Fig_10.png|thumb|400px|{{figure number|10}}Various pathways through which radon gas can migrate to the surface and into buildings (Finkelman et al, 2010b).]]

[[File:UNN_Medical_Geology_Fig_10.png|thumb|400px|{{figure number|10}}]]

Radon is a colourless inert gas formed from the radioactive disintegration of radium –the radioactive daughter of uranium. It has been established that there is a link between the levels of radon emitted by the rocks and that emitted by soils. The level of radon emitted by any rock depends on the quantity of uranium it contains which occurs in association with other minerals such as gold, phosphate and copper. This explains the scourge of lung cancer amongst uranium miners, as radon is carcinogenic. Radon emitted from most rocks travel to the surface through fractures and faults (Finkelman et al, 2010b). Its movement into buildings occurs through foundation cracks, cracks in the floor and walls below and above the surface. It can also enter through gaps in timber floors and around pipe fittings ([[:File:UNN_Medical_Geology_Fig_10.png|Figure 10]]).

African countries that have uranium as a natural resource include: South Africa which has the largest deposit of uranium in the continent–241,000 metric tons, Niger, Namibia, Gabon, Algeria, Botswana, Central African Republic, Chad. Others are: Egypt, Nigeria, Morocco, Mali, Madagascar, Malawi, Togo, Tanzania, Mauritania, Somalia, Guinea, Zambia and Lesotho (Davies, 2010).

African countries that have uranium as a natural resource include: South Africa which has the largest deposit of uranium in the continent–241,000 metric tons, Niger, Namibia, Gabon, Algeria, Botswana, Central African Republic, Chad. Others are: Egypt, Nigeria, Morocco, Mali, Madagascar, Malawi, Togo, Tanzania, Mauritania, Somalia, Guinea, Zambia and Lesotho (Davies, 2010).