Radon: a question of risk

Although radon has long been recognised as a danger in underground mines, ill-health caused by radioactivity of radon in houses has only recently been found to be a cause for concern. The source of the radon, its isotopic nature, the decay processes involved and the units of radiation doses are explained. The number of people in the UK who die each year as the result of exposure to radon is estimated at between 350 and 900. Although potentially the highest dose levels occur in areas where the ground contains large amounts of uranium and thorium (eg Devon and Cornwall), the actual levels of radon in a house are not necessarily related directly to this. The extent of fracturing in the ground and groundwater flow is also important and the major factor is the house design. Good underfloor ventilation and gaps round doors to reduce the amount of radon entering and assist its exit are important. Solid foundations and efficient draught proofing keeps the radon inside a house. There is much work to be done in obtaining the necessary detailed geological information about radon levels and in identifying those houses which have high radon levels and need, therefore, to be modified. (U.K.)