Uses a model to estimate the incremental risk of lung cancer associated with increased radon concentrations in indoor air resulting from decreased air infiltration caused by increased air tightness of dwellings. Gives results for selected changes in the air exchange rate. Discusses findings.
Recent work by the National Radiological Protection Board indicates that higher than average levels of exposure due to radon occur in the South West. West Devon District Council has undertaken its own survey on radon concentrations to see whether these can be associated with lung cancer incidence. The control of radon gas is likely to have implications for building structure and ventilation. There is a potential conflict between the desirability of increasing ventilation to cut radon levels on the one hand and reducing air infiltration to save energy on the other.
Indoor radon concentrations are approximately lognormally distributed, with the range of concentrations varying from a one in one thousand risk of contracting lung cancer to high one per cent risk. Source strength rather than ventilation rate seems to be the major factor causing the broad distribution in concentrations. There is general agreement that the most important mechanism for radon entry into homes is not diffusion but pressure driven flow of soil gas that carries radon from the soil into the homes.
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